[SS*]

(Original post by racheatworld)
You are exactly right, lactose permease increases the uptake of lactose. Lactose, as soon as it is in the environment, will be taken up by the cell, but the 2 enzymes are synthesised to increase this uptake and then to hydrolyse lactose so that the bacteria can use the lactose as a respiratory substrate.

(Original post by The Illuminati)
Sorry, I misunderstood the question. That is right though.

Thank you both

[Fatima0065]

Hi guys..me and darxangel have made all the relevant spec notes and put them togetehr..darx angel is going to put them up: have fun reading them..it took us alot of time and effort so hope you appreciate them

[Fatima0065]

(Original post by Lomas)
Non-reproductive cloning, also known as therapeutic cloning involves the creation if genetically identical tissues and cells that can be used in replacement of organ transplantation- the immune system is less likely to reject them as they are genetically identical and arent classed as foreign.

Reproductive cloning is the creation of un-genetically identical organisms.. I dont know what else you would say for reproductive cloning?


Define Asepsis and include some Asepsis techniques carried out

asepsis used to prevent contamination. in small scale asespsis is used: steam sterilisig at 121 degrees and using uv light and using airfume cupboards to circulate air and remove airbone contamination from bench surfaces
large scale:
wash, dienfect and stemclean to remove all microgranism and remove any product etc
use polis surfaces, to prevent bacteria sticking etc...inlets and outlets to avid microoganism entering and leaving
as you can tell..i need to go ove rhtis lool

[Fatima0065]

Hi guys..me and darxangel have made all the relevant spec notes and put them togetehr..darx angel is going to put them up: have fun reading them..it took us alot of time and effort so hope you appreciate them

[darkxangel]

By

(Original post by Fatima0065)

and

me-

(Original post by darkxangel)

explain the meaning of the term genetic code;
-genes code for polypeptides including proteins and enzymes,
-sequence of nucleotide bases on a gene provides a code, with instructions for the construction of the polypeptide or protein,
-it’s a triplet code, with each codon coding for an amino acid, four bases arranged in groups of three,
-it’s degenerate, because more than one codon could code for same amino acid,
-some indicate stop,
-it’s widespread, Codons generally always code for the same amino acid
in every organism, but this is not always the case.


• explain how mutations can have beneficial, neutral or harmful effects on the way a protein functions;
-Mutation is the RANDOM change to the sequence of nucleotides in DNA molecules,
-can consist of base deletion, addition (frame shift), substitution (point shift), inversion, repetition,
-somatic mutations will NOT be passed on to offspring-mitosis,
-in meiosis, gamete formation, the mutation WILL be passed on to offspring,-INHERITED,
-it’s beneficial if the mutation changes the sequence of nucleotides, therefore the phenotype and this gives the organism an advantageous characteristic,
-it’s harmful if the mutation changes the sequence of nucleotides, therefore the phenotype and this gives the organism a disadvantagous characteristic,

Neutral effects:
-mutation is on non-coding region of DNA,
-silent mutation- although base triplet has changed, it codes for the same amino acid,
-if the mutation does cause a change in the structure of protein, and therefore a different characteristic, but that particular characteristic gives no benefit/advantage or disadvantage then it’s neutral as well,
Example:
-early humans in Africa had very dark skin, because they had large amounts of the pigment melanin,
-melanin offered them protection against harmful uv light, which is a carcinogen,
-the light intensity in Africa was strong enough for their skin still to be able to synthesis vitamin-D,
-any mutation that caused paler skin (albinism) would have made them burn and given them sun-cancer,
-as humans migrated to temperate climes, the sunlight was less intense, not intense enough for people with darker skin to produce vitamin D,
-humans with mutations producing paler skin had a selective advantage,
-inuit people have retained their darker skin, because they diet is rich in vitamin D-seal/fish and blubber,
Negative effect:
Huntington disease:
-base pair repetition, CAG/expanded triplet pair, if number is higher than threshold number then protein is altered sufficiently, dementia and loss of motor control,
Cystic fibrosis:
-mutation is the deletion of a triplet code-deletion of an amino acid,
Sickle Cell anaemia:
-point-mutation of gene in b-polypeptide chains of haemoglobin, valine inserted instead of glutamic acid,
-growth promoting genes are called proto-oncogens, it can change it to oncogens, which can’t be switched off, unregulated cell division can lead to tumour,


• state that cyclic AMP activates proteins by altering their three-dimensional structure;

-cyclic AMP activates proteins by altering their three-dimensional structure, so that they are a better fit to their complimentary molecules,


• describe, with the aid of diagrams and photographs, the behaviour of chromosomes during meiosis, and the associated behaviour of the nuclear envelope, cell membrane and centrioles. (Names of the main stages are expected, but not the subdivisions of prophase);

MEIOSIS:
-1:
Prophase:
-chromatin condense and undergo supercoiling so that chromosomes shorten and thicken,
-they come together in the homologous pairs and to form a bivalent,
-non sister chromatids wrap around each other and attach at points called chiasmata,
-crossing over-they may swap alleles of the same genes/chromatids,
-nucleolus disappears, nuclear envelope disintegrates, spindle forms,
Metaphase:
-bivalents line up across equator of the spindle,
-they are arranged randomly, with each pair of the homologous pair facing opposite poles,
-this allows chromosomes to independently segregate when they are pulled apart in the next stage,
Anaphase:
-centromeres DON’T divide, the spindle fibre pull the homologous chromosomes in each bivalent to opposite poles,
-the chiasmata separate and length of chromatid that have been crossed over remain with the chromatid to which they’ve become newly attached,


Telophase:
-two new nuclear envelope form-one around each set of chromosomes at each pole-brief interphase and the chromosomes uncoil,



2:
Prophase:
-nuclear envelope disintegrates, nucleoulus disappears, spindle forms, chromosomes condense,
Metaphase:
-the chromosomes arrange themselves on the equator of the spindle, they are attached to spindle fibres at the centromeres,
-chromatids are randomly assorted,
Anaphase:
-centromeres DIVIDE, and the chromatid are pulled to opposite poles, the chromatids randomly segregate,
Telophase:
-nuclear envelopes reform around the haploid daughter nuclei,
-in animals the two cells now divide to give four haploid cells,
-in plants, a tetrad of four haploid cells is formed,

• explain the terms allele, locus, phenotype, genotype, dominant, codominant and recessive;
-allele: a different version of same gene with a difference in the DNA base sequence,,
-locus: the specific position of gene on chromosome,
-phenotype: observable characteristic, expressed gene,
-genotype: the alleles it (cells of individual) contains for a specific gene,
dominant: the allele that is always expressed in the phenotype even in heterozygous genotypes,
-recessive: allele is only expressed in the presence of another recessive allele or the absence of dominant allele,
-codominant: when alleles are combined in the expression of characteristic, both alleles contribute to phenotype


• explain the terms linkage and crossing-over;
linkage:
-refers to two or more gens that are located on the same chromosome, they are normally inherited together, because they do not segregate independently-unless chiasmata has been formed between them,
-at cross-over the alleles from one chromatid become linked to alleles on the other chromatid, linkage reduces the number of phenotype resulting from cross,
-Genes for different characteristics that are present at different loci on the same
chromosome are linked
Crossing over:
-when alleles at chiasmata on different chromosomes but same loci are swapped over,
-Where non-sister chromatids exchange alleles during prophase I of meiosis,

• explain how meiosis and fertilisation can lead to variation through the independent assortment of alleles;
-consequence of the random distribution of maternal and paternal chromosomes on the spindle equator in metaphase 1, and the subsequent segregation into two daughter nuclei at anaphase 1,
-each gamete acquires a different mixture of maternal and paternal chromosomes,
-random distribution on the spindle equator of the sister chromatids at metaphase 2,
-sister chromatids are no longer genetically identical, how they align at metaphase 2 determines how they segregate in anaphase 2,
-crossing over also increases variation, since alleles are swapped, so produces new combination of alleles of the same genes, crossing over ‘shuffles’ alleles
-Random mutations
-Fertilisation
-Randomly combining two sets of chromosomes, one from each of two genetically
unrelated individuals,


• describe the differences between continuous and discontinuous variation;
discontinuous:
-qualitative differences between phenotype-observable,
-differences fall into clearly distinguishable categories,
Continuous:
-quantitative differences between phenotypes, phenotypic differences where there is a wide range of variation within the population, with no distinct categories,

-both might be the result of more than one gene, however, in discontinuous variation, if there is more than one gene involved, the genes interact in an epistatic way,

• explain the basis of continuous and discontinuous variation by reference to the number of genes which influence the variation;
discontinuous:
-different alleles at a single gene locus have large effects on the phenotype,
-different gene loci have quite different effects on the phenotype,
-codominance, domimance, recessive patterns,
Continuous:
-controlled by two or more genes,
-each gene provides an additive element/component to the phenotype,
-different alleles at each gene locus have a small effect on the phenotype,
-large number of different genes may have combined effect of the phenotype, these are known as polygenes,


• explain why variation is essential in selection
-environment and genotype contribute to phenotypic variation,
-polygenic traits are more influenced by environment than monogenic traits,
-variation is essentially selection,


• explain, with examples, how environmental factors can act as stabilising or evolutionary forces of natural selection;
-In unchanging conditions, stabilising selection maintains existing adaptations and so maintains existing allele frequencies.
-In changing conditions, directional selection alters allele frequencies.
-A mutation may be disadvantageous in existing conditions, and so is removed in stabilising
selection, but if the conditions change, the mutation might be advantageous and selected for, meaning that selection becomes an evolutionary force-e.g. sunlight intensity and melanin/skin colour,


• explain how genetic drift can cause large changes in small populations;

-Genetic drift is a change in allele frequency that occurs by chance because only some of the organisms in each generation reproduce. It is particularly noticeable when a small number of individuals are separated from the rest of the large population. They form a small sample of the original population and so are unlikely to be representative of the large population’s gene pool.
-Genetic drift will alter the allele frequency still further.

• outline the differences between reproductive and non-reproductive cloning;
Reproductive cloning is the production of offspring which are genetically identical to either the
mother (nuclear transfer), or the other offspring (splitting embryos)
Non-reproductive cloning is the use of stem cells in order to generate replacement cells, tissues or
organs which may be used to treat particular diseases or conditions of humans

• describe how artificial clones of animals can be produced;
- Dairy cow
Each cow’s milk yield is measured and recorded
The progeny of bulls is tested to find out which bulls have produced daughters with high
milk yields
Only a few good-quality bulls need to be kept are the semen from one bull can be used to
artificially inseminate many cows
Some elite cows are given hormones so they produce many eggs
The eggs are fertilized in vitro and the embryos are implanted into surrogate mothers
These embryos could also be clones and divided into many more identical embryos
Bread wheat
Wheat can undergo polyplody- the nuclei can contain more than one diploid set of
chromosomes. Modern bread wheat is hexaploid, having 42 chromosomes in the nucleus
of each cell, meaning that the cells are bigger.
Nuclear transfer
A nucleus from an adult differentiated cell is placed in an enucleated egg cell. The egg then
goes through the stages of development using the genetic information from the inserted
nucleus
Splitting embryos
Cells from a developing embryo are separated out, with each one going on to produce a
separate, genetically identical organism

• discuss the advantages and disadvantages of cloning animals.
High value animals, e.g. cows giving a high milk yield, can be
cloned in high numbers
High value animals are not necessarily produced with animal
welfare in mind. Some strains of meat producing chickens jave
been developed that are unable to walk
Rare animals can be cloned to preserve the species As with plants, excessive genetic uniformity in a species makes it
unlikely to be able to cope with, or adapt to, changes in the
environment
Genetically modified animals- e.g. sheep that produce
pharmaceutical chemicals in their milk- can be quickly
reproduced
It is still unclear whether animals cloned using the nuclear
material of adult cells will remain healthy in the long term

• explain why microorganisms are often used in biotechnological processes;
- Grow rapidly in favourable conditions, with a generation time of as little as 30 minutes
Often produce proteins or chemicals that are given out into the surrounding medium and can be
harvested
Can be genetically engineered to produce specific products
Grow well are relatively low temperatures, much lower than those required in the chemical
engineering of similar processes
Can be grown anywhere in the world and are not dependent on climate
Tend to generate products that are in a more pure form than those generated via chemical
processes
Can often be grown using nutrient materials that would otherwise be useless or even toxic to
humans

• describe, with the aid of diagrams, and explain the standard growth curve of a microorganism in a closed culture;
- Lag phase
Organisms are adjusting to the surrounding conditions. This may mean taking in water, cell
expansion, activating specific genes and synthesising specific enzymes. The cells are active
but not reproducing so population remains fairly constant. The length of this period
depends on the growing conditions
Log phase
The population size doubles each generation as each individual has enough space and
nutrients to reproduce. In some bacteria the population can double every 20-30 mins. The
length of this phase depends on how quickly the organisms reproduce and take up the
available space and nutrients
Stationary phase
Nutrient levels decrease and waste products like Carbon Dioxide and other metabolites
build up. Individual organisms die at the same rate at which new individuals are being
produced. In an open system this would be the carrying capaciry
Death phase
Nutrient exhaustion and increased levels of toxic waste products and metabolites leads to
the death rate increasing above the reproduction rate. Eventually all of the organisms will
die in a close system


• outline the steps involved in sequencing the genome of an organism;

- Genomes are first mapped, to find out where the genome has come from microsatellites are used.
- Sections of DNA are sheared into small sections of 100 000 base pairs. This is sometimes known as the shotgun approach.
- These sections are placed into BAC’s (bacterial artificial chromosomes) and then transferred into E.coli where they form clone libraries.
- In order to sequence the BAC:
- Cells containing specific BAC’S are taken and cultured. The DNA cells are then cut into fragments using restriction enzymes. These are then placed into gel electrophoresis where they are separated.
- Each fragment is sequenced using an automated process
- Computer then compares overlapping regions.
• outline how gene sequencing allows for genome-wide comparisons between individuals and between species;
- Knowledge of genomes allows the structure of proteins to be established. Vital proteins can be identified if there is similar base sequence in a lot of organisms.
- Comparing the genomes of organisms shows evolutionary relationships between species. The more DNA sequences they hare the more closely related they are.
- Comparing genomes from pathogenic and similar but non-pathogenic organisms can be sued to identify which genes and base sequence cause certain disease, which can lead to developing more effective drugs.
- Comparing genomes can help us see how organisms evolve by identifying mutations etc.


• define the term recombinant DNA;

A section of DNA, often in a form of a plasmid, which is formed by joining DNA sections from two different sources.

• describe how DNA probes can be used to identify fragments containing specific sequences;
- DNA probes are small section of DNA, around 50-80 base pairs. They are single stranded and are labelled with either fluorescent markers (which glows with exposure to UV light) or radioactive markers (which are usually revealed by exposure to a photographic film).They are added to DNA, and because they are singled stranded they form complementary base pairs to the DNA being investigated, hence this is called annealing. As a result the position of the DNA sequence is identified.

• state other vectors into which fragments of DNA may be incorporated;

- Viral DNA- Advantages: long stability and good at injecting DNA into host cells but can be seen as foreign by organism immune system so can be destroyed
- -Liposomes- fat soluble so can cross phospholipid bilayer
- Bacteria and Plasmids

• explain how plasmids may be taken up by bacterial cells in order to produce a transgenic microorganism that can express a desired gene product;

calcium ions to dissolve membrane and break the peptidoglycan cell wall
- Heat shock, temperature put to 0 degrees and then heated to 40 degrees very quickly.
- Forming transformed/transgenic bacteria. (Less than 1% take up the plasmid).

• describe the advantage to microorganisms of the capacity to take up plasmid DNA from the environment;
-antibiotic resistance can spread, bacteria swap plasmid dna, plasmids are associated with antibiotic resistance,

• outline how genetic markers in plasmids can be used to identify the bacteria that have taken up a recombinant plasmid;
DNA Probes are used to locate the mRNA coding for the insulin
- mRNA is obtained from the islet of Langerhans.
- Reverse transcriptase is used to form cDNA.
- Unpaired nucleotides are added to each end of the CDNA forming sticky ends.
- CDNA is then mixed with the plasmid which has sticky end
- The sticky ends form complementary bases pars
- DNA Ligase is used to seal the phosphodiester backbone.
- This is now a recombinant DNA.
- Bacteria take up plasmid and this is placed on an agar plate, where it grows and forms clones.

• outline the process involved in the genetic engineering of bacteria to produce human insulin;

-Scientists focused on finding the mRNA strand coding for the insulin gene, and once it was located, the enzyme known as reverse transcriptase was used to synthesise a complementary DNA strand, which is single-stranded. -Once this has been isolated, free nucleotides and DNA polymerase are added to the insulin gene in order to make that single-stranded molecule double-stranded as the enzyme builds a complementary second strand, producing a copy of the original gene, called a cDNA gene.
-Plasmids from the bacterium E. coli are used in this process: they are cut open at specific points using restriction enzymes, and then the cDNA (which has unpaired nucleotides on either end, called sticky ends, allowing for annealing) is mixed with the open plasmids and the DNA ligase enzyme. Some of the plasmids will simply reseal themselves using DNA ligase, but some will take on the insulin gene, becoming recombinant plasmids, which can then be mixed with bacteria so that they take up the recombinant plasmids

• outline how animals can be genetically engineered for xenotransplantation;
-refers to transplantation of cell tissues or organs between animals of different species of different species whereas allotransplantation refers to transplantation between animals of the same species,
-Pigs have been engineered to lack the enzyme α-1,3-transferase, which is a key trigger for rejection of organs in humans,
-The human nucleotidase enzyme has been grafted into pig cells in culture. It reduces the number of immune cell activities involved in xenotransplant rejection
-immunorepressants are needed after surgery for lifetime of organ, toprevent rejection and immune response,
-religuous groups might object-pork/pig is considered unclean/pure in jewish and imuslim faith,
-medical concerns about it-like not knowing long-term effects, side-effects,
-it’s unnatural to move genes between organisms or to clone individual organisms or parts o organisms leads to the production of organisms, but humans have produced unnatural organisms for centuries-selective breeding,

• explain the term gene therapy;
-Refers to any therapeutic technique where the functioning allele of a particular gene is placed in the cells of an individual lacking the functioning alleles of that particular gene. Can be used to treat some recessive conditions, but not dominant conditions,
- Somatic cell gene therapy only affects the body cells. A dominant allele is added so it is more likely to be expressed in the organism by transcription and translation.
- Germ line cell therapy affect the germ line cells so the allele coding for function allele is passed onto the offspring. In the UK it is banned as it changes the genetic makeup of the organism. It may also have unknown adverse effects.

• discuss the ethical concerns raised by the genetic manipulation of animals (including humans), plants and microorganisms.
Religious objections
Objections to tampering with an organism’s natural genotype
Fears of unforeseen effects of the gene
Fears of the consequences of escape into the wild
Growing GM plants might damage the environment
Eating GM plants might be bad for health,

• state that ecosystems are dynamic systems;
-ecosystems are dynamic system,
A group of living and non-living organism living to getehr and the ineterelationship between them is reffered to an ecosystem
- It consists of 3 factors:
- Habitat- place where an organism lives
- Population: refers to the entire organism of the same species living together that can interbreed.
- Community: population of different species living together that can interact with each other.
Ecosystems are dynamic:
- Population sizes are fluctuating. If predator goes up prey goes down.
- Nitrogen fixing plants can increase nitrogen in depleted soils so the amount of plants increases as more plants grow there.


• define the terms biotic factor and abiotic factor
-abiotic: effects of non-living components of ecosystem on organisms, soil ph, temperature,
-biotic: effect of living components of ecosystem on organisms, e.g. predation, intra/interspecies competition, food supply, disease,

• explain how human activities can manipulate the flow of energy through ecosystems;
light levels:
-plant crops earlier for longer growing season,
-light-banks,
Water:
-irrigating crops,
-breeding drought-resistant crops,
Temperature:
-can limit the speed of chemical reactions in a plant,
-greenhouses,
Nutrients:
-rhizobium/nitrogen fixing crops,
-annual crop rotation,
-fertilisers,
- Deflecting natural succession to maintain grassland,
-eat calves instead of cows-since they have more energy,
-increase milk yield,
-removal of pests, fungal disease, weeds by herbi/pesti/fungicides,
-diseases/damaging pathogens,
-selective breeding,
Describe how human activities can manipulate the flow of energy through ecosystems:
- In plants: Humans can grow plants by monoculture, meaning they can grow one variety of plant in a single area so that maximise light etc hits these plant, maximising yield.
- Fertiliser are added to produce high protein yield in plants
- Herbicides to kill weed so they cannot compete
- Light banks are used or plants are grown in early times in the year to harvest enough light for photosynthesis
- Greenhouses are used for temperate to allow photosynthesis to occur
- Insects remove the amount of biomass in a plant so insecticides are used to kill them, reducing loss of biomass

• describe one example of primary succession resulting in a climax community
A sand dune:
Pioneer plants such as sea rocket colonies the sand just above the high water mark. These
can tolerate salt water spray, lack of fresh water and unstable sand
Wind-blown sand builds up around the base of these plants, forming a ‘mini’ sand dune. As
the plants die and decay, nutrients accumulate in this mini dune. As they dune gets bigger,
plants like sea couch grass colonise it, which has underground stems to help stabilise the
sand
With more stability and accumulation of more nutrients, plants like marram grass start to
grow. Marram grass shoots trap windblown sand and, as the sand accumulated, the shoots
grow taller to stay above the growing dune, thus trapping more sand.
As the sand dune and nutrients build up, other plants colonise the sand. Many are
members of the bean family, which have nodules in their roots which contain bacteria
which convert nitrogen to nitrates. With nitrates available, more species colonise the
dunes, stabilising them further

Rock:
Algae and lichens begin to living on the bare rock
Erosion of the rock and build up of dead and rotting organisms produces enough soil for
larger plants, such as mosses and fern to grow
Larger plants succeed the small plants until the climax community is reached

• explain that conservation is a dynamic process involving management and reclamation;
-The idea of preserving an area of land is no good
- Active management is needed, this is called conservation, for example if you had a pond and left it exactly how it is without managing it, then it would eventually cease to be a pond.
- Conservation also involves maintain biodiversity and sustaining natural resources.
-successful conservation requires consideration of the social and economic costs to the local community, as well as effective education and liaison with the community,
-it can involve establishing protected areas like national parks or sites of scientific interest, it can involve giving legal protection to endangered species, or conserving them ex-situ in zoos or botanic gardens,
-maintaining biodiversity requires careful management to maintain a stable community or even to reclaim an ecosystem by reversing the effects of human activity,
Management strategies:
-raise carrying capacity by providing extra food,
-control predators and poaching,
-vaccinate individuals against disease,
-preserve habitat by preventing pollution or disruption, or intervene to restrict progress of succession,
-more individuals to enlarge population,
-moving individuals to increase population or encouraging natural dispersion of individuals between fragmented habitats by developing dispersal corridors of appropriate habitats,
-decreasing dispersal of individuals by fencing,

• outline, with examples, the effects of human activities on the animal and plant populations in the Galapagos Islands.

-whaling boats and poachers harvested whales and seals to sell them internationally,
-giant tortoise numbers were reduced, because they were taken on boats since they could survive on little food and water in the hold of a ship for a long time before they were killed and eaten,
-captive breeding programmes were introduced to replenish tortoise numbers,
-Dramatic increase in population size has placed huge demand on water, energy and
sanitation services
More waste and pollution have been produce
The demand for oil has increased
2001 oil spill had an adverse effect on marine and costal ecosystems
Increased pollution, building and conversion of land for agriculture has caused destruction
and fragmentation of habitats
Species have been harvested faster than they could replenish themselves.
-expanding demand for lobster and sea cucumber had adverse effect on marine life,
Introduced species:
-cats were natural predators to many species including lizards,
-goats eat rock purslane and out-compete tortoises by trampling on their nesting sites and grazing on their food supplies,
Management:
-they search arriving boats and tourists for foreign species,
-culling has been successful against feral goats,
-any conservation plan has to take concerns of local people seriously,
-finding balance between social, economical and environmental concerns is essential


• explain how plant responses to environmental changes are co-ordinated by hormones, with reference to responding to changes in light direction;
Plants release hormones; these are called plant growth regulators and act as chemical messengers. They flow in the plant by active transport, diffusion, and mass flow in phloem or xylem vessels. Some plants respond to light intensity. This is called phototropism; this enables them to photosynthesise more.
-Plants respond to external stimuli as well as biotic and abiotic components of the environment to
help the plant avoid stress, being eaten, and survive long enough to reproduce. These responses are
coordinated by hormones
The presence of auxin promotes the active transport of hydrogen ions through the ATPase enzyme,
into the cell wall. This decreases the pH and allows optimum conditions for the wall loosening
enzymes to work. These enzymes break bonds within the cellulose, so the walls become less rigid
and can expand as the cells take in water.
A shoot bends towards a light source because auxin in transported to the tip o the shoot to the cells
in the shade, allowing the cells to take up more water and elongate.
Because the cells elongate more on the shaded side than the side in the light, the shoot bends
towards the light source
(d) evaluate the experimental evidence
• discuss why animals need to respond to their environment;
-Because they need to maintain a constant environment so need to respond to changes in the internal and external environment. They also need to responds to danger. All of these response ensures that the mammal survives
-Animals need to respond to their environment to stay alive. This is done using nerves and
hormones, to control responses ranging from muscle actions to run away from a predator, to fine
control of balance, posture and temperature regulation.
• describe the role of the brain and nervous system in the co-ordination of muscular movement;
-The conscious decision to move voluntarily is initiated in the cerebellum. Neurones from the cerebellum carry impulses to the motor areas so that motor output to the effectors can be adjusted appropriately in these requirements,

• describe how co-ordinated movement requires the action of skeletal muscles about joints, with reference to the movement of the elbow joint;
-biceps and triceps act antagonistically,
-synovial joint occur where large degrees of movement is required, synovial fluid is a lubricant that eases the movement,
-impulse arrives at neuromuscular junction, vesicles fuse with membrane, acetylcholine is released in the gap, it fuses with receptor on sacrolemna, impulse travels down tubules/t-system, ca ions are released from sarcoplasmic reticulum, power-stroke occurs, ca-ions are actively transported by co-transporter proteins to SR,

• explain, with the aid of diagrams and photographs, the sliding filament model of muscular contraction;
-myosin head group on thick filament attaches to thin actin, atp is hydrolysed, cross-bridge forms, head-group bends and makes actin overlap more with thick filament-power stroke, atp is hydrolysed to break cross-bridge,
-tropomyosin block binding site for myosin head group, calcium ion binds to troponin complex, which changes shape of tropomyosin and binding site is free for myosin head group,

• outline the role of ATP in muscular contraction, and how the supply of ATP is maintained in muscles;
-aerobic respiration in mitochondria muscle cells,
-anaerobic respiration in sarcoplasm, this leads to production of lactic acid, which increases blood flow to muscle cells,
-creatine-phosphate transfer, phosphate group attaches to adp in sarcoplasm, with the help of enzyme phospotransferace,

• state that responses to environmental stimuli in mammals are co-ordinated by nervous and endocrine systems;
-responses to environmental stimuli in mammals are co-ordinated by nervous and endocrine systems,

[otrivine]

wooooooooooooooooooooooooooooooo oooooooow this is the whole book hahaha ++++rep

[stressedoutbadly247]

does anyone have a list of potential big markers? (e.g 8-10 mark questions like protein synthesis, producing insulin)

[darkxangel]

(Original post by stressedoutbadly247)
does anyone have a list of potential big markers? (e.g 8-10 mark questions like protein synthesis, producing insulin)

Here you go, I made some notes on these big topics

Spoiler:

Show

Behaviour:
Imprinting:
-young animals become associated with another organisms usually the parent, only occurs in the sensitive period,/receptive period, i.e. ducklings,

Learned Behaviour:
-animal responses that change or adapt with experience,
-range of learned behaviour such simply not responding to stimulation, to the ability to consider a problem a problem and formulate a solution,
-with a longer lifespan and so time to learn,
-parental care of the young, living for a part of time with another member of same species,
-main advantage is that's it's adapted in response to changing circumstances or environments,

Habituation:
-animals learn to ignore certain stimuli, because repeated exposure to the stimulus results in neither reward nor a punishment,

Classical Conditional:
-a conditional stimulus leads to a new reflex and conditioned response. This is called classical conditioning, where animals can learn relate a pair of events and respond to the first in anticipation of the second-passive and involuntary,dog-bell-food,

Latent exploratory learning
-animals will explore new surroundings and retain information about their surroundings that is not of immediate use but may be essential to staying alive at some future time, i.e. rabbits and burrows,

Operant conditioning:
-active and to an extent 'voluntary' learning,
-trial and error learning,
-specific behavioural reaction to stimulus by adding an element of reward or punishment, it associates the stimulus/operation with the reward or punishment (reinforces) -i.e. cat, lever, freedom/food/shock,

Insight learning:
-highest form of learning, based on the ability to think and reason in order to solve their problems a responses, or to do deal with situations in ways that do not resemble simple, fixed reflexor the need for trial and error.

Innate Behaviour:
-response that increases its chances of survival (inherit response),

advantages:
-genetically determined and so environment has no impact on behavioural response, passed on to offspring via reproduction,
-rigid and inflexible,
-patterns of behaviour are the same in all members of a species,
-unintelligent in the sense that the organism probably has no sense of the purpose of the behaviour,
-innate behaviour is inherited in the genome of an organism,
-escape predators, locate and stay in suitable environment and locate habitat, (invertebrates)

reflexes:
many invertebrates have an escape reflex, the functions of which is to avoid predators,

kinesis:
-orientation behavioural where the rate of movement increases when the organism is in favourable conditions-non-directional, it's to change the rate of movement in relation to intensity of stimulus, not in any particular direction,

taxes:
-a taxis is a 'directional' orientation response, the direction of movement is described in relation to the stimulus which triggers the behavioural response, (phototaxis, chemotaxis)

more complex innate behaviour:
-linking together of a series of innate behaviours gives some complex behaviour patterns in vertebrates,

specific example for each:-
-Imprinting = Goslings imprinting on first living thing they see and will follow and learn off organisms that look like it in future
-Habituation = Pigeons in big cities, learning not to get scared of traffic noises or can use humans in cities sleeping with traffic noises.
-Classical = Pavlov's dogs investigation
-Operant = Skinners box (rats using levers to get rewards)
-Latent = Rabbits only showing they learnt the burrows when needed e.g when running from predators
-Insight = Chimpanzees using boxes to get to bananas on ceiling as they were toys they had played with before.

-Escape reflex - Worms when the go deeper into the soil when feel vibrations
-Kineses = Woodlice when in dry + light areas increased movement rate
-Taxes = Also woodlice directional movement into a more favourable environment (Damp and Dark)


Social behaviour in primates:
hierarchy:
-within a group exists where individuals have a place in the order of the importance within the group. This is often shown by individuals higher up in the hierarchy receiving more food, or having rights of access to mate with other individuals,

Gorillas:
-mountain gorillas live in groups of about ten individuals called troops,, which usually consists of one mature male and a number of adult females and their offspring,
-the older male protects the others, leads them in search of food and is the only male that mates with the mature females,
-individuals pick the parasites from the fur of another, which reinforces the relationships between individuals,
-during the first months and infant remains in constant contact with the mother, during this period the mother protects the infant whilst it learns the social and other skills necessary to live independently,
-a variety of calls, displays and runts are used to signal danger to other members of the group, to issue threats to predators or other groups,

-females give birth to only on or very few infants at a time, the maternal care and group protection enhance the survival rate of the young,
-the young learn through observation and play with the other members of the group-learned behaviour is vital to the survival of primates,
-the final relatively large brain size slows the maturation of primates,
-knowledge and protection of food sources is shared between group,
-greater ability to detect and deter predators by groups of individuals working together,

-skin-to-skin contact, breastfeeding on demand, constant contact with mother enhances speed of learning from the mother and aids the social development of the infant through the ability to learn the social structures and activities in safety-carry behaviour,

Human Behaviour:
-it's thought that the inheritance of particular variants of the DRD4 gene affects the levels and action of dopamine in the brain,

ADHD:
-drugs such as ritalin used to treat ADHD affect dopamine levels in the brain,

Additive and Risk:
-articular variants of DRD4 receptor gene are implicated in increased likelyhood of additive behaviours including smoking and gambling,

DRD4:
-it's one of five genes that code for dopamine receptor molecules,
-dopamine can bind to each of the five receptors, but each have differing effects, because they lead to different cellular responses,

-dopamine acts as a neurotransmitter and a hormone,
-it's precursor molecule in the production of adrenaline and noradrenaline,
-abnormal low-levels are associated with parkinsons-the treatment by admission of L-dopa is associated with schizophrenia,
-increases arousal, decreases inhibition and increases creativity,
-five different dopamine receptors, each code for a separate gene,

Spoiler:

Show

Muscles:
-three types, cardiac, skeletal, smooth,
cardiac muscles:
-myogenic,
-pump blood around body,
-medulla oblongata control cardiac centre,
-atrial and ventricular muscles,
-specialised excitatory and conductive muscle tissue: purkinje tissue, wave of excitation, AVN,
-longer duration of contractcion,

Voluntary/skeletal/striated muscle:
-found in skeletal muscles,
sacromere-smallest contractile unit of muscle,
-leads to movement of the skeletons at the joints,
-sacroplasm, sacroplasmic reticulum contains calcium ions,
-many mitochondria and microfibrils,

involuntary muscles:
-smooth muscles in connected to neurones of the autonomic system-not under conscious control,
-peristalsis-movement of food along the intestine,
-radial muscles contract pupils dilate, circular muscles contract pupil constrict,
wall of arterioles, cervix of uterus,
-circular bundles-temperature regulation, local blood pressure, redirecting blood to voluntary muscles, relaxation causes dilation->increased blood flow,

Muscle contraction:
neuromuscular junction:
-impulse arrives, vesicles fuse with pre-synaptic membrane, acetyl-choline is released, binds to receptors on post-synaptic neurone/sacrolemna, depolarisation travels down tubules (t-system), sacroplasmic reticulum is stimulated to release calcium ions, calcium ions bind to protein ions in muscles
-power stroke,
-acetyl-cholinesterase in the gap actively breaks down acetyl-choline, so contraction occurs only if impulses arrive continuously,

sliding filament model:
thin filament:
consist chiefly of the protein f-actin, coiled around each other like a double-string of beads, each string is made up of g-actin/globular subunits,
-tropomyosin is coiled around f-actin reinforcing it, a troponin complex is attached to each tropomyosin,
-each troponin complex consists of three binding sites, one for tropomyosin, one for actin and one for calcium ions,

thick filament:
-consists of bundles of protein myosin, each myosin consists of one tail and two protruding heads,

The power stroke:
-myosin head group attaches to surrounding actin filaments forming a crossbridge,
-the head group then bends, pulling the actin with it, so the thin actin overlaps more with the thick one, atp is hydrolysed,
-cross-bridge is then broken as new atp attaches to myosin, the head group moved backwards as atp is hydrolysed, so it can form a new cross-bridge with actin further along,

-in a contracting muscle-millions of cross-bridges are being continuously formed and broken, causing the thin filament to slide past thick filament, which shortens the length of sacromere (span from one z-line to the other)-this shortens whole length of muscle.

role of calcium ions:
-the binding site for myosin head is blocked by tropomyosin on actin,
-calcium ions bind to troponin complex, which changes shape of tropomyosin and causes it to dissociate, meaning that the binding site for myosin is free, cross-bridges can be formed and contraction occurs,
-calcium ions are released by sacroplasmic reticulum and diffuse through the sacroplasm to bind to troponin complex,
-when nervous stimulation stops calcium ions are actively transported back into the SR by carrier proteins,

Elbow movement:
-synovial joint allows large degree of movement, synovial fluid lubricates it for easier/smoother movement,
-biceps and triceps act antagonistically,

control of contraction:
-the nervous system controls muscle action, since motor neurones are connected to muscle cells at a neuromuscular junction, impulses arriving at junction stimulate contraction, the neuromuscular junction is a specialised synapse that occurs at the end of motor neurone where it meets with muscle fibre,

motor unit:
-some muscular movement require stronger contraction than others, the brain controls the strength of contraction, because many other motor neurones stimulate a single muscle, each one branches to neuromuscular junctions, causing the contraction ofa cluster of muscle cells-known as motor unit, the more motor units stimulised the greater the force of contraction, gradation of response,

Role of ATP:
-when myosin head group attaches to actin and breaks the molecules are at their most stable form,
-energy from atp is required to break the cross-bridge,

-only sufficient atp available in a muscle fibre to support perhaps 1-2 seconds worth of contraction,
-so atp must be regenerated,

-aerobic respiration in muscle cell mitochondria,
-anaerobic respiration in the muscle cell sacroplasm, which leads to production of lactic acid-where it leads to increased blood supply to the muscles,
-transfer of creatine phosphate in the muscle cell sacroplasm, phosphate group is joined to adp to form atp with the hel o enzyme creatine phosphotransferace,

Spoiler:

Show

Genome Sequencing
-genomes are first mapped to identify which part of chromosomes they come from,
-info already known is used such as microsatelites,
-samples of the genomes are mechanically sheared into smaller fragments,
-each section is placed in separate bacterial artificial chromosomes,
-it's transferred to bacteria E.coli where it's grown in cultures-clonal libraries

-cells containing specific BAC sections are treated with restriction enzymes and cut into small fragments,
-the use of different restriction enzymes on a number of samples gives different fragment types,
-electrophoresis is used to separate fragments,
-each fragment is sequenced using an automated process,
-computer programmes analyse overlapping regions from the cuts of different restriction enzymes to reassemble the whole BAC sequence,

-to ensure that the assembled code is accurate, sequencing is carried out a number of times on different overlapping fragments, and the overlapping regions are analysed and put back together to form the complete code,

Comparing Genomes:
-viruses and similar non-pathogenic organisms can be compared to help identify the base pair sequence that is responsible/most important for causing disease-help with more effective target treatment and vaccines,
-comparing genomes between different species can help identify evolutionary relationships, the more base-air sequence they share, the closer related they are,
-the identification of genes for proteins found in all or many organisms can help us to understand more about the importance of such genes to life,
-DNA of individuals can be analysed to identify/reveal mutated alleles and the likelihood of certain diseases,

electrophoresis
-dna samples/fragments are placed in well cut into negative end of agarose gel dish, the solution is covered by buffer solution,
-a current is passed through for a duration of time (usually 2 hours)
-dna fragments diffuse towards the positive (attracted to it)end/anode, because if the many phosphoryl groups they contain that gives them a negative charge,
-smaller/shorter lengths of fragments move faster, and so move further in that fixed amount of time the current is passed through,
-the position of the fragment can be shown using a dye that stains DNA,

DNA Probes:
-copies of the robe can be added to any sample of dna fragments and since they're single stranded, they will bind to any fragment where a complimentary base sequence is present-annealing,
-it can be used to locate a specific desired gene that is wanted for genetic engineering,
-to identify the same gene on a variety of different genomes from separate species when conducting genome comparison studies,
-to identify the presence of absence of specific alleles for a particular genetic disease,

-radioactive markers,
-fluorescent markers (both automated and PCR),

southern blotting:
a nylon or nitrocellulose sheet is placed over the gel (in electrophoresis), covered in paper towels, pressed and left overnight, dna fragments are transferred to the sheet and can now be analysed,

automated sequencing:
-reaction mixture contains enzyme DNA polymerase, many copies of the singlestranded template fragment, free nucleotides and primers some of which contain fluorescent markers,

-the primer molecules anneals at the 3"end of the template strand allowing dna polymerase to attach,
-dna polymerase attaches free nucleotides according to base pairing rules,
-if a modified nucleotide is added, then dna polymerase is thrown off and the reaction stops on that template strand,
-as the reaction proceeds many molecules of dna are made,
-the fragments generally vary in size,
-in some of the template strands only one additional nucleotide is added before polymerase is thrown off, in others the template strand is completed,
-the final nucleotide is tagged with a specific colour,
-as the sample is passed through a machine a laser reads the colour sequence from small strand to bigger strand,


PCR
-artificial dna sequencing
-dna strands, primers, free nucleotides dna polymerase are used,
-temperature is raised to 95C, hydrogen bonds break, strands untwists and unzips, bases are left exposed, temperature is lowered to 55C, primers anneal to complimentary bases on single dna strand, hydrogen bonds form, primers only grow on 3"end, temperature is raised to 72C, dna polymerase attaches to dna and attach nucleotides on strand and extend the strand until they are thrown off at the end, a new double stranded DNA is formed,
-dna polymerase is said to be thermophillic just because it is not denatured at extreme temperatures,


Genetic Engineering:
-enzymes known as restriction enzymes are used to cut through dna at specific points,
-a particular restriction enzymes cut where specific base sequence occur and only there-restriction site,
-the enzyme catalyses a hydrolysis racyion which break the sugar-phosphate backbone of the DNA double helix in different places gicing it a staggered cut,-leading to form exposed bases referred to as a sticky end,
-when separate DNA fragments need to be stuck together, DNA ligase catayses a condensation reaction in order to join dna fragments (from different sources) cut with the same restriction, so complimentary sticky ends, this type of dna is called recombinant dna,

Transgenic micro-organism:
-once a gene has been isolated/identified it can be placed into organism, it can be cut by restricion enzyme and then placed into vector,
-plasmids are cut with same restriction enzymes, so that isolated ene and plasmid have complimentary sticky ends,
- mixing quantities of plasmid and gene in the presence of ligase enzyme means some of the plasmids will combine with the gene,which is becoming sealed with the plasmid to form a recombinant plasmid,
-large quantities of bacterial cells are mixed with recombinant plasmids, some of which will take up the recombinant plasmid,
-addition of calcium salts and heat shock (freezing->40degrees)increase the rate of plasmid uptake,
-bacteria that have taken up recombinant plasmid are transformed and said to be transgenic,
-many cut plasmids in the presence of ligase enzymes will simply reseal to reform the original plasmid,

advantage of plasmid uptake:
-bacteria are capable of conjugation, where genetic material may be exchanged,
-in this process copies of plasmid dna are passed between bacteria,
-since plasmids often carry genes associated with resistance to antibiotics, it speeds the spread of antibiotic resistance between bacterial populations,


Replica Plating:
-insulin can be extracted from b-cell if islets of langerhans in the pancreas,
-not all bacteria will take the reformed plasmids, some take up original plasmid, and others don't take up plasmid,

-the original plasmids are chosen because they carry genes that make any bacteria receiving them resistant to two different antibiotics-tetracycline and ampicillin, they are known as genetic markers
-the bacteria (E-coli are susceptible to both these markers,)
-plasmids are cut with same restriction enzyme that has its target site-c restriction site-in the middle o the tetracycline resistant gene, so that if the required gene is taken up, the tetracycline gene will break/ and resistance won't work,
-however resistance for ampicillin still works,

the bacteria are grown on standard nutrient agar, so all bacteria form colonies,
-some cells from the colonies are transferred onto agar that has been made with ampicilin so only those who have taken up a plasmid will grown, some cells from the colonies are transferred onto agar made with tetracycline so only those that have take up a plasmid with no gene will grow,
-others,
-by keeping track of which is which, we can identify which bacteria have recombinant plasmid with required gene,
-those cells that grow on ampicillin but not tetracycline will have insulin gene,
-these bacteria can produce insulin on a large scale which can be harvested for use,


Extraction of genes and placing them into genome
-genetic engineering involves the extraction of genes from one organism and placing them into another organism,

-required gene is isolated and obtained, it's packaged into vector. vector carries gene into recipient cell. the recipient cell expresses the gene through protein synthesis,

-gene can be sealed into virus, viral transfer,
-microinjection,
-liposomes,
-electroporation,

Reverse Transcriptase:
-some viruses carry their genetic material as RNA,
-when they infect cell, they acuse enzyme reverse transcriptase to be synthesised on the host cell ribosomes, this enzyme copies the viral rna back to form dna,

[Lomas]

(Original post by stressedoutbadly247)
does anyone have a list of potential big markers? (e.g 8-10 mark questions like protein synthesis, producing insulin)

I think an explanation of PCR or Genome sequencing may come up as I haven't seen a question asked on them recently, other long questions could include; Cloning of animals, Galapagos island, sustainable management and maybe coordinated movement and muscles

[otrivine]

(Original post by darkxangel)
Here you go, I made some notes on these big topics

Spoiler:

Show

Behaviour:
Imprinting:
-young animals become associated with another organisms usually the parent, only occurs in the sensitive period,/receptive period, i.e. ducklings,

Learned Behaviour:
-animal responses that change or adapt with experience,
-range of learned behaviour such simply not responding to stimulation, to the ability to consider a problem a problem and formulate a solution,
-with a longer lifespan and so time to learn,
-parental care of the young, living for a part of time with another member of same species,
-main advantage is that's it's adapted in response to changing circumstances or environments,

Habituation:
-animals learn to ignore certain stimuli, because repeated exposure to the stimulus results in neither reward nor a punishment,

Classical Conditional:
-a conditional stimulus leads to a new reflex and conditioned response. This is called classical conditioning, where animals can learn relate a pair of events and respond to the first in anticipation of the second-passive and involuntary,dog-bell-food,

Latent exploratory learning
-animals will explore new surroundings and retain information about their surroundings that is not of immediate use but may be essential to staying alive at some future time, i.e. rabbits and burrows,

Operant conditioning:
-active and to an extent 'voluntary' learning,
-trial and error learning,
-specific behavioural reaction to stimulus by adding an element of reward or punishment, it associates the stimulus/operation with the reward or punishment (reinforces) -i.e. cat, lever, freedom/food/shock,

Insight learning:
-highest form of learning, based on the ability to think and reason in order to solve their problems a responses, or to do deal with situations in ways that do not resemble simple, fixed reflexor the need for trial and error.

Innate Behaviour:
-response that increases its chances of survival (inherit response),

advantages:
-genetically determined and so environment has no impact on behavioural response, passed on to offspring via reproduction,
-rigid and inflexible,
-patterns of behaviour are the same in all members of a species,
-unintelligent in the sense that the organism probably has no sense of the purpose of the behaviour,
-innate behaviour is inherited in the genome of an organism,
-escape predators, locate and stay in suitable environment and locate habitat, (invertebrates)

reflexes:
many invertebrates have an escape reflex, the functions of which is to avoid predators,

kinesis:
-orientation behavioural where the rate of movement increases when the organism is in favourable conditions-non-directional, it's to change the rate of movement in relation to intensity of stimulus, not in any particular direction,

taxes:
-a taxis is a 'directional' orientation response, the direction of movement is described in relation to the stimulus which triggers the behavioural response, (phototaxis, chemotaxis)

more complex innate behaviour:
-linking together of a series of innate behaviours gives some complex behaviour patterns in vertebrates,

specific example for each:-
-Imprinting = Goslings imprinting on first living thing they see and will follow and learn off organisms that look like it in future
-Habituation = Pigeons in big cities, learning not to get scared of traffic noises or can use humans in cities sleeping with traffic noises.
-Classical = Pavlov's dogs investigation
-Operant = Skinners box (rats using levers to get rewards)
-Latent = Rabbits only showing they learnt the burrows when needed e.g when running from predators
-Insight = Chimpanzees using boxes to get to bananas on ceiling as they were toys they had played with before.

-Escape reflex - Worms when the go deeper into the soil when feel vibrations
-Kineses = Woodlice when in dry + light areas increased movement rate
-Taxes = Also woodlice directional movement into a more favourable environment (Damp and Dark)


Social behaviour in primates:
hierarchy:
-within a group exists where individuals have a place in the order of the importance within the group. This is often shown by individuals higher up in the hierarchy receiving more food, or having rights of access to mate with other individuals,

Gorillas:
-mountain gorillas live in groups of about ten individuals called troops,, which usually consists of one mature male and a number of adult females and their offspring,
-the older male protects the others, leads them in search of food and is the only male that mates with the mature females,
-individuals pick the parasites from the fur of another, which reinforces the relationships between individuals,
-during the first months and infant remains in constant contact with the mother, during this period the mother protects the infant whilst it learns the social and other skills necessary to live independently,
-a variety of calls, displays and runts are used to signal danger to other members of the group, to issue threats to predators or other groups,

-females give birth to only on or very few infants at a time, the maternal care and group protection enhance the survival rate of the young,
-the young learn through observation and play with the other members of the group-learned behaviour is vital to the survival of primates,
-the final relatively large brain size slows the maturation of primates,
-knowledge and protection of food sources is shared between group,
-greater ability to detect and deter predators by groups of individuals working together,

-skin-to-skin contact, breastfeeding on demand, constant contact with mother enhances speed of learning from the mother and aids the social development of the infant through the ability to learn the social structures and activities in safety-carry behaviour,

Human Behaviour:
-it's thought that the inheritance of particular variants of the DRD4 gene affects the levels and action of dopamine in the brain,

ADHD:
-drugs such as ritalin used to treat ADHD affect dopamine levels in the brain,

Additive and Risk:
-articular variants of DRD4 receptor gene are implicated in increased likelyhood of additive behaviours including smoking and gambling,

DRD4:
-it's one of five genes that code for dopamine receptor molecules,
-dopamine can bind to each of the five receptors, but each have differing effects, because they lead to different cellular responses,

-dopamine acts as a neurotransmitter and a hormone,
-it's precursor molecule in the production of adrenaline and noradrenaline,
-abnormal low-levels are associated with parkinsons-the treatment by admission of L-dopa is associated with schizophrenia,
-increases arousal, decreases inhibition and increases creativity,
-five different dopamine receptors, each code for a separate gene,

Spoiler:

Show

Muscles:
-three types, cardiac, skeletal, smooth,
cardiac muscles:
-myogenic,
-pump blood around body,
-medulla oblongata control cardiac centre,
-atrial and ventricular muscles,
-specialised excitatory and conductive muscle tissue: purkinje tissue, wave of excitation, AVN,
-longer duration of contractcion,

Voluntary/skeletal/striated muscle:
-found in skeletal muscles,
sacromere-smallest contractile unit of muscle,
-leads to movement of the skeletons at the joints,
-sacroplasm, sacroplasmic reticulum contains calcium ions,
-many mitochondria and microfibrils,

involuntary muscles:
-smooth muscles in connected to neurones of the autonomic system-not under conscious control,
-peristalsis-movement of food along the intestine,
-radial muscles contract pupils dilate, circular muscles contract pupil constrict,
wall of arterioles, cervix of uterus,
-circular bundles-temperature regulation, local blood pressure, redirecting blood to voluntary muscles, relaxation causes dilation->increased blood flow,

Muscle contraction:
neuromuscular junction:
-impulse arrives, vesicles fuse with pre-synaptic membrane, acetyl-choline is released, binds to receptors on post-synaptic neurone/sacrolemna, depolarisation travels down tubules (t-system), sacroplasmic reticulum is stimulated to release calcium ions, calcium ions bind to protein ions in muscles
-power stroke,
-acetyl-cholinesterase in the gap actively breaks down acetyl-choline, so contraction occurs only if impulses arrive continuously,

sliding filament model:
thin filament:
consist chiefly of the protein f-actin, coiled around each other like a double-string of beads, each string is made up of g-actin/globular subunits,
-tropomyosin is coiled around f-actin reinforcing it, a troponin complex is attached to each tropomyosin,
-each troponin complex consists of three binding sites, one for tropomyosin, one for actin and one for calcium ions,

thick filament:
-consists of bundles of protein myosin, each myosin consists of one tail and two protruding heads,

The power stroke:
-myosin head group attaches to surrounding actin filaments forming a crossbridge,
-the head group then bends, pulling the actin with it, so the thin actin overlaps more with the thick one, atp is hydrolysed,
-cross-bridge is then broken as new atp attaches to myosin, the head group moved backwards as atp is hydrolysed, so it can form a new cross-bridge with actin further along,

-in a contracting muscle-millions of cross-bridges are being continuously formed and broken, causing the thin filament to slide past thick filament, which shortens the length of sacromere (span from one z-line to the other)-this shortens whole length of muscle.

role of calcium ions:
-the binding site for myosin head is blocked by tropomyosin on actin,
-calcium ions bind to troponin complex, which changes shape of tropomyosin and causes it to dissociate, meaning that the binding site for myosin is free, cross-bridges can be formed and contraction occurs,
-calcium ions are released by sacroplasmic reticulum and diffuse through the sacroplasm to bind to troponin complex,
-when nervous stimulation stops calcium ions are actively transported back into the SR by carrier proteins,

Elbow movement:
-synovial joint allows large degree of movement, synovial fluid lubricates it for easier/smoother movement,
-biceps and triceps act antagonistically,

control of contraction:
-the nervous system controls muscle action, since motor neurones are connected to muscle cells at a neuromuscular junction, impulses arriving at junction stimulate contraction, the neuromuscular junction is a specialised synapse that occurs at the end of motor neurone where it meets with muscle fibre,

motor unit:
-some muscular movement require stronger contraction than others, the brain controls the strength of contraction, because many other motor neurones stimulate a single muscle, each one branches to neuromuscular junctions, causing the contraction ofa cluster of muscle cells-known as motor unit, the more motor units stimulised the greater the force of contraction, gradation of response,

Role of ATP:
-when myosin head group attaches to actin and breaks the molecules are at their most stable form,
-energy from atp is required to break the cross-bridge,

-only sufficient atp available in a muscle fibre to support perhaps 1-2 seconds worth of contraction,
-so atp must be regenerated,

-aerobic respiration in muscle cell mitochondria,
-anaerobic respiration in the muscle cell sacroplasm, which leads to production of lactic acid-where it leads to increased blood supply to the muscles,
-transfer of creatine phosphate in the muscle cell sacroplasm, phosphate group is joined to adp to form atp with the hel o enzyme creatine phosphotransferace,

Spoiler:

Show

Genome Sequencing
-genomes are first mapped to identify which part of chromosomes they come from,
-info already known is used such as microsatelites,
-samples of the genomes are mechanically sheared into smaller fragments,
-each section is placed in separate bacterial artificial chromosomes,
-it's transferred to bacteria E.coli where it's grown in cultures-clonal libraries

-cells containing specific BAC sections are treated with restriction enzymes and cut into small fragments,
-the use of different restriction enzymes on a number of samples gives different fragment types,
-electrophoresis is used to separate fragments,
-each fragment is sequenced using an automated process,
-computer programmes analyse overlapping regions from the cuts of different restriction enzymes to reassemble the whole BAC sequence,

-to ensure that the assembled code is accurate, sequencing is carried out a number of times on different overlapping fragments, and the overlapping regions are analysed and put back together to form the complete code,

Comparing Genomes:
-viruses and similar non-pathogenic organisms can be compared to help identify the base pair sequence that is responsible/most important for causing disease-help with more effective target treatment and vaccines,
-comparing genomes between different species can help identify evolutionary relationships, the more base-air sequence they share, the closer related they are,
-the identification of genes for proteins found in all or many organisms can help us to understand more about the importance of such genes to life,
-DNA of individuals can be analysed to identify/reveal mutated alleles and the likelihood of certain diseases,

electrophoresis
-dna samples/fragments are placed in well cut into negative end of agarose gel dish, the solution is covered by buffer solution,
-a current is passed through for a duration of time (usually 2 hours)
-dna fragments diffuse towards the positive (attracted to it)end/anode, because if the many phosphoryl groups they contain that gives them a negative charge,
-smaller/shorter lengths of fragments move faster, and so move further in that fixed amount of time the current is passed through,
-the position of the fragment can be shown using a dye that stains DNA,

DNA Probes:
-copies of the robe can be added to any sample of dna fragments and since they're single stranded, they will bind to any fragment where a complimentary base sequence is present-annealing,
-it can be used to locate a specific desired gene that is wanted for genetic engineering,
-to identify the same gene on a variety of different genomes from separate species when conducting genome comparison studies,
-to identify the presence of absence of specific alleles for a particular genetic disease,

-radioactive markers,
-fluorescent markers (both automated and PCR),

southern blotting:
a nylon or nitrocellulose sheet is placed over the gel (in electrophoresis), covered in paper towels, pressed and left overnight, dna fragments are transferred to the sheet and can now be analysed,

automated sequencing:
-reaction mixture contains enzyme DNA polymerase, many copies of the singlestranded template fragment, free nucleotides and primers some of which contain fluorescent markers,

-the primer molecules anneals at the 3"end of the template strand allowing dna polymerase to attach,
-dna polymerase attaches free nucleotides according to base pairing rules,
-if a modified nucleotide is added, then dna polymerase is thrown off and the reaction stops on that template strand,
-as the reaction proceeds many molecules of dna are made,
-the fragments generally vary in size,
-in some of the template strands only one additional nucleotide is added before polymerase is thrown off, in others the template strand is completed,
-the final nucleotide is tagged with a specific colour,
-as the sample is passed through a machine a laser reads the colour sequence from small strand to bigger strand,


PCR
-artificial dna sequencing
-dna strands, primers, free nucleotides dna polymerase are used,
-temperature is raised to 95C, hydrogen bonds break, strands untwists and unzips, bases are left exposed, temperature is lowered to 55C, primers anneal to complimentary bases on single dna strand, hydrogen bonds form, primers only grow on 3"end, temperature is raised to 72C, dna polymerase attaches to dna and attach nucleotides on strand and extend the strand until they are thrown off at the end, a new double stranded DNA is formed,
-dna polymerase is said to be thermophillic just because it is not denatured at extreme temperatures,


Genetic Engineering:
-enzymes known as restriction enzymes are used to cut through dna at specific points,
-a particular restriction enzymes cut where specific base sequence occur and only there-restriction site,
-the enzyme catalyses a hydrolysis racyion which break the sugar-phosphate backbone of the DNA double helix in different places gicing it a staggered cut,-leading to form exposed bases referred to as a sticky end,
-when separate DNA fragments need to be stuck together, DNA ligase catayses a condensation reaction in order to join dna fragments (from different sources) cut with the same restriction, so complimentary sticky ends, this type of dna is called recombinant dna,

Transgenic micro-organism:
-once a gene has been isolated/identified it can be placed into organism, it can be cut by restricion enzyme and then placed into vector,
-plasmids are cut with same restriction enzymes, so that isolated ene and plasmid have complimentary sticky ends,
- mixing quantities of plasmid and gene in the presence of ligase enzyme means some of the plasmids will combine with the gene,which is becoming sealed with the plasmid to form a recombinant plasmid,
-large quantities of bacterial cells are mixed with recombinant plasmids, some of which will take up the recombinant plasmid,
-addition of calcium salts and heat shock (freezing->40degrees)increase the rate of plasmid uptake,
-bacteria that have taken up recombinant plasmid are transformed and said to be transgenic,
-many cut plasmids in the presence of ligase enzymes will simply reseal to reform the original plasmid,

advantage of plasmid uptake:
-bacteria are capable of conjugation, where genetic material may be exchanged,
-in this process copies of plasmid dna are passed between bacteria,
-since plasmids often carry genes associated with resistance to antibiotics, it speeds the spread of antibiotic resistance between bacterial populations,


Replica Plating:
-insulin can be extracted from b-cell if islets of langerhans in the pancreas,
-not all bacteria will take the reformed plasmids, some take up original plasmid, and others don't take up plasmid,

-the original plasmids are chosen because they carry genes that make any bacteria receiving them resistant to two different antibiotics-tetracycline and ampicillin, they are known as genetic markers
-the bacteria (E-coli are susceptible to both these markers,)
-plasmids are cut with same restriction enzyme that has its target site-c restriction site-in the middle o the tetracycline resistant gene, so that if the required gene is taken up, the tetracycline gene will break/ and resistance won't work,
-however resistance for ampicillin still works,

the bacteria are grown on standard nutrient agar, so all bacteria form colonies,
-some cells from the colonies are transferred onto agar that has been made with ampicilin so only those who have taken up a plasmid will grown, some cells from the colonies are transferred onto agar made with tetracycline so only those that have take up a plasmid with no gene will grow,
-others,
-by keeping track of which is which, we can identify which bacteria have recombinant plasmid with required gene,
-those cells that grow on ampicillin but not tetracycline will have insulin gene,
-these bacteria can produce insulin on a large scale which can be harvested for use,


Extraction of genes and placing them into genome
-genetic engineering involves the extraction of genes from one organism and placing them into another organism,

-required gene is isolated and obtained, it's packaged into vector. vector carries gene into recipient cell. the recipient cell expresses the gene through protein synthesis,

-gene can be sealed into virus, viral transfer,
-microinjection,
-liposomes,
-electroporation,

Reverse Transcriptase:
-some viruses carry their genetic material as RNA,
-when they infect cell, they acuse enzyme reverse transcriptase to be synthesised on the host cell ribosomes, this enzyme copies the viral rna back to form dna,

wow thanks
can u ask me questions?

[Lomas]

(Original post by Fatima0065)
asepsis used to prevent contamination. in small scale asespsis is used: steam sterilisig at 121 degrees and using uv light and using airfume cupboards to circulate air and remove airbone contamination from bench surfaces
large scale:
wash, dienfect and stemclean to remove all microgranism and remove any product etc
use polis surfaces, to prevent bacteria sticking etc...inlets and outlets to avid microoganism entering and leaving
as you can tell..i need to go ove rhtis lool

Yeah that's right in the textbook it just says;
- work carried out in a fume cupboard
- wash and disinfect the fermenter when not in use, steam clean also carried out
- surfaces made of stainless steel to prevent microbes from sticking to surfaces
- steralise all nutrient media before adding it to the fermenter

[Fatima0065]

(Original post by Lomas)
Yeah that's right in the textbook it just says;
- work carried out in a fume cupboard
- wash and disinfect the fermenter when not in use, steam clean also carried out
- surfaces made of stainless steel to prevent microbes from sticking to surfaces
- steralise all nutrient media before adding it to the fermenter

thanks

[stressedoutbadly247]

(Original post by darkxangel)
Here you go, I made some notes on these big topics

Spoiler:

Show

Behaviour:
Imprinting:
-young animals become associated with another organisms usually the parent, only occurs in the sensitive period,/receptive period, i.e. ducklings,

Learned Behaviour:
-animal responses that change or adapt with experience,
-range of learned behaviour such simply not responding to stimulation, to the ability to consider a problem a problem and formulate a solution,
-with a longer lifespan and so time to learn,
-parental care of the young, living for a part of time with another member of same species,
-main advantage is that's it's adapted in response to changing circumstances or environments,

Habituation:
-animals learn to ignore certain stimuli, because repeated exposure to the stimulus results in neither reward nor a punishment,

Classical Conditional:
-a conditional stimulus leads to a new reflex and conditioned response. This is called classical conditioning, where animals can learn relate a pair of events and respond to the first in anticipation of the second-passive and involuntary,dog-bell-food,

Latent exploratory learning
-animals will explore new surroundings and retain information about their surroundings that is not of immediate use but may be essential to staying alive at some future time, i.e. rabbits and burrows,

Operant conditioning:
-active and to an extent 'voluntary' learning,
-trial and error learning,
-specific behavioural reaction to stimulus by adding an element of reward or punishment, it associates the stimulus/operation with the reward or punishment (reinforces) -i.e. cat, lever, freedom/food/shock,

Insight learning:
-highest form of learning, based on the ability to think and reason in order to solve their problems a responses, or to do deal with situations in ways that do not resemble simple, fixed reflexor the need for trial and error.

Innate Behaviour:
-response that increases its chances of survival (inherit response),

advantages:
-genetically determined and so environment has no impact on behavioural response, passed on to offspring via reproduction,
-rigid and inflexible,
-patterns of behaviour are the same in all members of a species,
-unintelligent in the sense that the organism probably has no sense of the purpose of the behaviour,
-innate behaviour is inherited in the genome of an organism,
-escape predators, locate and stay in suitable environment and locate habitat, (invertebrates)

reflexes:
many invertebrates have an escape reflex, the functions of which is to avoid predators,

kinesis:
-orientation behavioural where the rate of movement increases when the organism is in favourable conditions-non-directional, it's to change the rate of movement in relation to intensity of stimulus, not in any particular direction,

taxes:
-a taxis is a 'directional' orientation response, the direction of movement is described in relation to the stimulus which triggers the behavioural response, (phototaxis, chemotaxis)

more complex innate behaviour:
-linking together of a series of innate behaviours gives some complex behaviour patterns in vertebrates,

specific example for each:-
-Imprinting = Goslings imprinting on first living thing they see and will follow and learn off organisms that look like it in future
-Habituation = Pigeons in big cities, learning not to get scared of traffic noises or can use humans in cities sleeping with traffic noises.
-Classical = Pavlov's dogs investigation
-Operant = Skinners box (rats using levers to get rewards)
-Latent = Rabbits only showing they learnt the burrows when needed e.g when running from predators
-Insight = Chimpanzees using boxes to get to bananas on ceiling as they were toys they had played with before.

-Escape reflex - Worms when the go deeper into the soil when feel vibrations
-Kineses = Woodlice when in dry + light areas increased movement rate
-Taxes = Also woodlice directional movement into a more favourable environment (Damp and Dark)


Social behaviour in primates:
hierarchy:
-within a group exists where individuals have a place in the order of the importance within the group. This is often shown by individuals higher up in the hierarchy receiving more food, or having rights of access to mate with other individuals,

Gorillas:
-mountain gorillas live in groups of about ten individuals called troops,, which usually consists of one mature male and a number of adult females and their offspring,
-the older male protects the others, leads them in search of food and is the only male that mates with the mature females,
-individuals pick the parasites from the fur of another, which reinforces the relationships between individuals,
-during the first months and infant remains in constant contact with the mother, during this period the mother protects the infant whilst it learns the social and other skills necessary to live independently,
-a variety of calls, displays and runts are used to signal danger to other members of the group, to issue threats to predators or other groups,

-females give birth to only on or very few infants at a time, the maternal care and group protection enhance the survival rate of the young,
-the young learn through observation and play with the other members of the group-learned behaviour is vital to the survival of primates,
-the final relatively large brain size slows the maturation of primates,
-knowledge and protection of food sources is shared between group,
-greater ability to detect and deter predators by groups of individuals working together,

-skin-to-skin contact, breastfeeding on demand, constant contact with mother enhances speed of learning from the mother and aids the social development of the infant through the ability to learn the social structures and activities in safety-carry behaviour,

Human Behaviour:
-it's thought that the inheritance of particular variants of the DRD4 gene affects the levels and action of dopamine in the brain,

ADHD:
-drugs such as ritalin used to treat ADHD affect dopamine levels in the brain,

Additive and Risk:
-articular variants of DRD4 receptor gene are implicated in increased likelyhood of additive behaviours including smoking and gambling,

DRD4:
-it's one of five genes that code for dopamine receptor molecules,
-dopamine can bind to each of the five receptors, but each have differing effects, because they lead to different cellular responses,

-dopamine acts as a neurotransmitter and a hormone,
-it's precursor molecule in the production of adrenaline and noradrenaline,
-abnormal low-levels are associated with parkinsons-the treatment by admission of L-dopa is associated with schizophrenia,
-increases arousal, decreases inhibition and increases creativity,
-five different dopamine receptors, each code for a separate gene,

Spoiler:

Show

Muscles:
-three types, cardiac, skeletal, smooth,
cardiac muscles:
-myogenic,
-pump blood around body,
-medulla oblongata control cardiac centre,
-atrial and ventricular muscles,
-specialised excitatory and conductive muscle tissue: purkinje tissue, wave of excitation, AVN,
-longer duration of contractcion,

Voluntary/skeletal/striated muscle:
-found in skeletal muscles,
sacromere-smallest contractile unit of muscle,
-leads to movement of the skeletons at the joints,
-sacroplasm, sacroplasmic reticulum contains calcium ions,
-many mitochondria and microfibrils,

involuntary muscles:
-smooth muscles in connected to neurones of the autonomic system-not under conscious control,
-peristalsis-movement of food along the intestine,
-radial muscles contract pupils dilate, circular muscles contract pupil constrict,
wall of arterioles, cervix of uterus,
-circular bundles-temperature regulation, local blood pressure, redirecting blood to voluntary muscles, relaxation causes dilation->increased blood flow,

Muscle contraction:
neuromuscular junction:
-impulse arrives, vesicles fuse with pre-synaptic membrane, acetyl-choline is released, binds to receptors on post-synaptic neurone/sacrolemna, depolarisation travels down tubules (t-system), sacroplasmic reticulum is stimulated to release calcium ions, calcium ions bind to protein ions in muscles
-power stroke,
-acetyl-cholinesterase in the gap actively breaks down acetyl-choline, so contraction occurs only if impulses arrive continuously,

sliding filament model:
thin filament:
consist chiefly of the protein f-actin, coiled around each other like a double-string of beads, each string is made up of g-actin/globular subunits,
-tropomyosin is coiled around f-actin reinforcing it, a troponin complex is attached to each tropomyosin,
-each troponin complex consists of three binding sites, one for tropomyosin, one for actin and one for calcium ions,

thick filament:
-consists of bundles of protein myosin, each myosin consists of one tail and two protruding heads,

The power stroke:
-myosin head group attaches to surrounding actin filaments forming a crossbridge,
-the head group then bends, pulling the actin with it, so the thin actin overlaps more with the thick one, atp is hydrolysed,
-cross-bridge is then broken as new atp attaches to myosin, the head group moved backwards as atp is hydrolysed, so it can form a new cross-bridge with actin further along,

-in a contracting muscle-millions of cross-bridges are being continuously formed and broken, causing the thin filament to slide past thick filament, which shortens the length of sacromere (span from one z-line to the other)-this shortens whole length of muscle.

role of calcium ions:
-the binding site for myosin head is blocked by tropomyosin on actin,
-calcium ions bind to troponin complex, which changes shape of tropomyosin and causes it to dissociate, meaning that the binding site for myosin is free, cross-bridges can be formed and contraction occurs,
-calcium ions are released by sacroplasmic reticulum and diffuse through the sacroplasm to bind to troponin complex,
-when nervous stimulation stops calcium ions are actively transported back into the SR by carrier proteins,

Elbow movement:
-synovial joint allows large degree of movement, synovial fluid lubricates it for easier/smoother movement,
-biceps and triceps act antagonistically,

control of contraction:
-the nervous system controls muscle action, since motor neurones are connected to muscle cells at a neuromuscular junction, impulses arriving at junction stimulate contraction, the neuromuscular junction is a specialised synapse that occurs at the end of motor neurone where it meets with muscle fibre,

motor unit:
-some muscular movement require stronger contraction than others, the brain controls the strength of contraction, because many other motor neurones stimulate a single muscle, each one branches to neuromuscular junctions, causing the contraction ofa cluster of muscle cells-known as motor unit, the more motor units stimulised the greater the force of contraction, gradation of response,

Role of ATP:
-when myosin head group attaches to actin and breaks the molecules are at their most stable form,
-energy from atp is required to break the cross-bridge,

-only sufficient atp available in a muscle fibre to support perhaps 1-2 seconds worth of contraction,
-so atp must be regenerated,

-aerobic respiration in muscle cell mitochondria,
-anaerobic respiration in the muscle cell sacroplasm, which leads to production of lactic acid-where it leads to increased blood supply to the muscles,
-transfer of creatine phosphate in the muscle cell sacroplasm, phosphate group is joined to adp to form atp with the hel o enzyme creatine phosphotransferace,

Spoiler:

Show

Genome Sequencing
-genomes are first mapped to identify which part of chromosomes they come from,
-info already known is used such as microsatelites,
-samples of the genomes are mechanically sheared into smaller fragments,
-each section is placed in separate bacterial artificial chromosomes,
-it's transferred to bacteria E.coli where it's grown in cultures-clonal libraries

-cells containing specific BAC sections are treated with restriction enzymes and cut into small fragments,
-the use of different restriction enzymes on a number of samples gives different fragment types,
-electrophoresis is used to separate fragments,
-each fragment is sequenced using an automated process,
-computer programmes analyse overlapping regions from the cuts of different restriction enzymes to reassemble the whole BAC sequence,

-to ensure that the assembled code is accurate, sequencing is carried out a number of times on different overlapping fragments, and the overlapping regions are analysed and put back together to form the complete code,

Comparing Genomes:
-viruses and similar non-pathogenic organisms can be compared to help identify the base pair sequence that is responsible/most important for causing disease-help with more effective target treatment and vaccines,
-comparing genomes between different species can help identify evolutionary relationships, the more base-air sequence they share, the closer related they are,
-the identification of genes for proteins found in all or many organisms can help us to understand more about the importance of such genes to life,
-DNA of individuals can be analysed to identify/reveal mutated alleles and the likelihood of certain diseases,

electrophoresis
-dna samples/fragments are placed in well cut into negative end of agarose gel dish, the solution is covered by buffer solution,
-a current is passed through for a duration of time (usually 2 hours)
-dna fragments diffuse towards the positive (attracted to it)end/anode, because if the many phosphoryl groups they contain that gives them a negative charge,
-smaller/shorter lengths of fragments move faster, and so move further in that fixed amount of time the current is passed through,
-the position of the fragment can be shown using a dye that stains DNA,

DNA Probes:
-copies of the robe can be added to any sample of dna fragments and since they're single stranded, they will bind to any fragment where a complimentary base sequence is present-annealing,
-it can be used to locate a specific desired gene that is wanted for genetic engineering,
-to identify the same gene on a variety of different genomes from separate species when conducting genome comparison studies,
-to identify the presence of absence of specific alleles for a particular genetic disease,

-radioactive markers,
-fluorescent markers (both automated and PCR),

southern blotting:
a nylon or nitrocellulose sheet is placed over the gel (in electrophoresis), covered in paper towels, pressed and left overnight, dna fragments are transferred to the sheet and can now be analysed,

automated sequencing:
-reaction mixture contains enzyme DNA polymerase, many copies of the singlestranded template fragment, free nucleotides and primers some of which contain fluorescent markers,

-the primer molecules anneals at the 3"end of the template strand allowing dna polymerase to attach,
-dna polymerase attaches free nucleotides according to base pairing rules,
-if a modified nucleotide is added, then dna polymerase is thrown off and the reaction stops on that template strand,
-as the reaction proceeds many molecules of dna are made,
-the fragments generally vary in size,
-in some of the template strands only one additional nucleotide is added before polymerase is thrown off, in others the template strand is completed,
-the final nucleotide is tagged with a specific colour,
-as the sample is passed through a machine a laser reads the colour sequence from small strand to bigger strand,


PCR
-artificial dna sequencing
-dna strands, primers, free nucleotides dna polymerase are used,
-temperature is raised to 95C, hydrogen bonds break, strands untwists and unzips, bases are left exposed, temperature is lowered to 55C, primers anneal to complimentary bases on single dna strand, hydrogen bonds form, primers only grow on 3"end, temperature is raised to 72C, dna polymerase attaches to dna and attach nucleotides on strand and extend the strand until they are thrown off at the end, a new double stranded DNA is formed,
-dna polymerase is said to be thermophillic just because it is not denatured at extreme temperatures,


Genetic Engineering:
-enzymes known as restriction enzymes are used to cut through dna at specific points,
-a particular restriction enzymes cut where specific base sequence occur and only there-restriction site,
-the enzyme catalyses a hydrolysis racyion which break the sugar-phosphate backbone of the DNA double helix in different places gicing it a staggered cut,-leading to form exposed bases referred to as a sticky end,
-when separate DNA fragments need to be stuck together, DNA ligase catayses a condensation reaction in order to join dna fragments (from different sources) cut with the same restriction, so complimentary sticky ends, this type of dna is called recombinant dna,

Transgenic micro-organism:
-once a gene has been isolated/identified it can be placed into organism, it can be cut by restricion enzyme and then placed into vector,
-plasmids are cut with same restriction enzymes, so that isolated ene and plasmid have complimentary sticky ends,
- mixing quantities of plasmid and gene in the presence of ligase enzyme means some of the plasmids will combine with the gene,which is becoming sealed with the plasmid to form a recombinant plasmid,
-large quantities of bacterial cells are mixed with recombinant plasmids, some of which will take up the recombinant plasmid,
-addition of calcium salts and heat shock (freezing->40degrees)increase the rate of plasmid uptake,
-bacteria that have taken up recombinant plasmid are transformed and said to be transgenic,
-many cut plasmids in the presence of ligase enzymes will simply reseal to reform the original plasmid,

advantage of plasmid uptake:
-bacteria are capable of conjugation, where genetic material may be exchanged,
-in this process copies of plasmid dna are passed between bacteria,
-since plasmids often carry genes associated with resistance to antibiotics, it speeds the spread of antibiotic resistance between bacterial populations,


Replica Plating:
-insulin can be extracted from b-cell if islets of langerhans in the pancreas,
-not all bacteria will take the reformed plasmids, some take up original plasmid, and others don't take up plasmid,

-the original plasmids are chosen because they carry genes that make any bacteria receiving them resistant to two different antibiotics-tetracycline and ampicillin, they are known as genetic markers
-the bacteria (E-coli are susceptible to both these markers,)
-plasmids are cut with same restriction enzyme that has its target site-c restriction site-in the middle o the tetracycline resistant gene, so that if the required gene is taken up, the tetracycline gene will break/ and resistance won't work,
-however resistance for ampicillin still works,

the bacteria are grown on standard nutrient agar, so all bacteria form colonies,
-some cells from the colonies are transferred onto agar that has been made with ampicilin so only those who have taken up a plasmid will grown, some cells from the colonies are transferred onto agar made with tetracycline so only those that have take up a plasmid with no gene will grow,
-others,
-by keeping track of which is which, we can identify which bacteria have recombinant plasmid with required gene,
-those cells that grow on ampicillin but not tetracycline will have insulin gene,
-these bacteria can produce insulin on a large scale which can be harvested for use,


Extraction of genes and placing them into genome
-genetic engineering involves the extraction of genes from one organism and placing them into another organism,

-required gene is isolated and obtained, it's packaged into vector. vector carries gene into recipient cell. the recipient cell expresses the gene through protein synthesis,

-gene can be sealed into virus, viral transfer,
-microinjection,
-liposomes,
-electroporation,

Reverse Transcriptase:
-some viruses carry their genetic material as RNA,
-when they infect cell, they acuse enzyme reverse transcriptase to be synthesised on the host cell ribosomes, this enzyme copies the viral rna back to form dna,

That's great thankyou!

[darkxangel]

(Original post by otrivine)
wow thanks
can u ask me questions?

i would but need to study for chem, it's tomorrow-i'll se ya at 8 ish

[darkxangel]

(Original post by stressedoutbadly247)
That's great thankyou!

no problemo!

[otrivine]

(Original post by darkxangel)
i would but need to study for chem, it's tomorrow-i'll se ya at 8 ish

shall we revise chem then ?

[I'm a Hobbit]

Hey guys,

The spec says "Describe how artifical selection has been used to produce the modern dairy cow and to produce bread wheat, Triticum auestivum"

The procedure for the cow is pretty staright forward but the procedure to produce bread wheat is vague in the purple textbook and isn't mentioned at all in the green textbook.

Was wondering how much of it we really need to know? Thanks

[darkxangel]

(Original post by otrivine)
shall we revise chem then ?

umm yes, that's a good idea-i'll be back in fifteen mins

[Lomas]

can someone recap what we need to know about cloning please

[AndyHoughton]

(Original post by Lomas)
can someone recap what we need to know about cloning please

You need to know about reproductive and non reproductive cloning, their uses and examples.

Vegetative propagation both natural and artificial including the example of root suckers in the English Elm.

Micropropagation (tissue culture)

Advantages and disadvantages of plant cloning.

Cloning animals: Splitting embryos and Nuclear Transfer (With Dolly the sheep, I think)

Advantages and disadvantages of animal cloning.