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    I'll post up some quick notes on cellular control!
    (1) Protein Synthesis
    What is a Gene? A gene is a length of DNA that codes for one or more polypeptides, they are mainly situated on the linear chromosomes in the nucleus.
    The Genetic Code - The sequence of bases found in a gene contains a code with the instructions for the construction of a polypeptide or protein. The code is a triplet code (3 bases code of one amino acid also known as a codon), the code is degenerate (reduces chances of a nonfunctioning protein being produced because of a point mutation), some codons are STOP codons, these indicate the end of a polypeptide chain.

    Ribosomes - Made my rRNA and protein, consist of 2 subunits and a groove into which a length of mRNA can fit
    tRNA - Forms in the nucleus and passes into the cytoplasm, has 3 unpaired bases at one end, this is an anticodon, it can bind temporaily to a complementary codon (hydrogen bonds), carries amino acids.

    Transcription First stage of protein synthesis, its is where mRNA is formed by using a strand of DNA (template strand)
    Translation Second stage of protein synthesis, in where the amino acid sequence is put together by using the sequence of codons that is dictated by the length of mRNA (english xD)
    In prokaryotes the process is a lot quicker because the DNA is naked and the mRNA doesn't have to exit the nucleus

    Summary
    SEQUENCE OF DNA BASES --> SEQUENCE OF AMINO ACIDS --> SHAPE AND FUNCTION OF PROTEIN --> CHARACTERISTICS OF THE CELL
    AS stuff: Look up DNA replication, structure of DNA and RNA
    (2) Mutations
    A random change to the genetic material, this can be a mutation to DNA (Point mutation, one base pair replaces another, or Deletion or Insertion - one or more bases are added to the length of DNA, this causes a frameshift. Effects of a deletion can be cancelled out by 2 more deletions or by a nearby insertion. Resulting effects can be neutral (characterstic brings about no disadvantage or advantage) Harmful ( resulting phenotype is harmful) and Beneficial. DNA muations can contribute to genetic diease.

    Effects of DNA mutations - Addition --> Causes a frameshift, different amino acid sequence, a different (usually non-fuctioning) protein is produced
    Deletion --> Causes a frameshift, alteration of codons from the point of deletion, a different (usually non-fuctioning) protein is produced
    Substitution --> Can lead to silent mutation, formation of a stop codon or a different amino acid sequence

    Substances that cause mutations are called mutagens.
    Extra info: Have a look at some examples

    (3) Homeobox Genes If anyone has any additional info on this, I would appreciate it, can't find much stuff on it

    Homeobox genes control the development of the body plans including the polarity and positing of the organs. Expressed in specific patterns at certain stages of development. Consists of 180 base pairs and these code for polypeptides of about 60 amino acids...some of these are transcription factors. They are arranged into clusters known as hox clusters. Mutation of these genes can change one body part to another. Morphagens govern the pattern of tissue development by activating the homeobox genes.

    (4) Apoptosis
    Process: Enzyme breaks down the Cell cytoskeleton, cytoplasm becomes dense with organelles tightly packed, cell surface membrane changes and blebs form, chormatin condense nuclear envelope breaks down and dna breaks into fragments, cell breaks down into vessicles that are taken up by phagocytosis and the cellular debris are disposed of so they do not harm any surrounding tissues or cells.

    It can occur when: a cell is damaged beyond repair, a cell is infected with a virus, or undergoing stress conditions like starvation. It removes the damaged cell, preventing it from sapping further nutrients or preventing the spread of infection.
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    Does anyone have the f215 june 2010 paper and mark scheme?

    Thanks, I give rep

    Edit: Found it, thanks to Waqar Y

    (Original post by Waqar Y)
    https://sites.google.com/a/kings-wto...-level-biology

    here, found a site which has it - i had it anyway but i cba emailing to anyone anymore LOL
    ^ rep him
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    Im looking for the paper also
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    (Original post by mathsclown)
    Looking for this? I went through them, they are great, but if you are going to go through them make sure you've got the text book handy, there are a few points missing, but other than that, they are a great set of notes
    Yeah, thats them! I am. Though its good if you can be bothered to read through it all!
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    (Original post by ibysaiyan)
    Yay AT LONG LAST SOMEONE POSTED HERE with some INTEREST... Right from what I can recall on chi square is that say if the value which we get is less than the critical value of 0.05 probability then it's safe to assume that null hypothesis is valid i.e we expect these difference to occur and are not by chance but if the value is greater than the critical value we reject null hypothesis,we need to reconsider our experiment.

    Genetic drift is the random/change shift in the number(set) of alleles of a population (definition for gene pool).The criteria for genetic drift to occur are:
    *No selection pressure/or low pressure.
    *Occurs RANDOMLY WITH no connection to natural selection
    *Anytime and in particular to small populations
    *More often in island places.
    How it all happens?
    basically you get few individuals in a small population who overtime by chance happen to survive better and hence reproduce on the contrast others who can't cope die.You end up with a chance of alleles in this population resulting in the change of charactersics.These alleles become dominant and hence shift the previous gene pool.
    =]]]]

    Founder effect is a special case of Genetic drift but in the OCR spec we don't need to know that.If you have any more follow on questions to this post of mine or anything to do with genetics/variation ,please quote me back.
    Good night it's almost 8 am xD

    EDIT: I just re read your post on chi square: the only genetic explanation to that is hm... I think mutation could be the reason for the differences OR polygenic inheritance to cause continuous variation =]
    Thanks .Okay, I think that kind of makes sense now, so are you saying that genetic drift is completely different from any kind of speciation? Also, im not sure what you mean by randomly with no connection to natural selection, isnt the fact that some individuals are surviving and others aren't natural selection? :confused: do you have an example, didnt quite understand the one in the text book, i think its the only thing in cellular control topic i dont quite get....also, havent quite come across any questions on this in the legacy papers.

    could linkage also be another reason for the devaition in the chi squared test, i dont know im just suggesting...

    what is the genetic explanation of continuous/discontiuous variation. is is just the former is polygenic and influenced by the envt, and the other is monogenic, or is there a bit more to it?

    personally, i think the content isnt so bad, im just worried about phrasing my answers, looking back at June 10, it wasnt such a tough paper, think I just hadnt revised as well or was daunted... im guessing though that muscle contraction might come up this time, maybe in an essay form as the specimen and the june 10 didnt have it...
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    (Original post by hazu121)
    Thanks .Okay, I think that kind of makes sense now, so are you saying that genetic drift is completely different from any kind of speciation? Also, im not sure what you mean by randomly with no connection to natural selection, isnt the fact that some individuals are surviving and others aren't natural selection? :confused: do you have an example, didnt quite understand the one in the text book, i think its the only thing in cellular control topic i dont quite get....also, havent quite come across any questions on this in the legacy papers.

    could linkage also be another reason for the devaition in the chi squared test, i dont know im just suggesting...

    personally, i think the content isnt so bad, im just worried about phrasing my answers, looking back at June 10, it wasnt such a tough paper, think I just hadnt revised as well or was daunted... im guessing though that muscle contraction might come up this time, maybe in an essay form as the specimen and the june 10 didnt have it...

    hmm, also think reading examiners report on ocr is quite helpful...just general tips
    It's in a sense isolation.What I mean't was that in directional selection (is where due to fluctuation the in the environment brought by the natural selection produces variation)in genetic drift that thing doesn't occur at all.Just out of random some individuals happen to be successful in this remotely population.
    I think you are confusing geographical isolation to genetic drift.
    P.S I am preparing for my maths exam tomorrow.Been distracted badly over the last 2 weeks :/
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    (Original post by ibysaiyan)
    It's in a sense isolation.What I mean't was that in directional selection (is where due to fluctuation the in the environment brought by the natural selection produces variation)in genetic drift that thing doesn't occur at all.Just out of random some individuals happen to be successful in this remotely population.
    I think you are confusing geographical isolation to genetic drift.
    P.S I am preparing for my maths exam tomorrow.Been distracted badly over the last 2 weeks :/
    OH! Okay, I get it know, thanks im just being stupid...

    okay, let you get back to your maths revision , thanks for answering my questions...
    oh and good luck for tomorrow
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    (Original post by Chunkeymonkey62)
    Yeah, thats them! I am. Though its good if you can be bothered to read through it all!
    Haha! Biology is my weakest subject not because I find it hard, it's just because I find it really boring lol and that means I have to proper force myself to revise
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    (Original post by jlcf)
    Does anyone have the f215 june 2010 paper and mark scheme?

    Thanks, I give rep

    Edit: Found it, thanks to Waqar Y



    ^ rep him

    Nice ! Just did the paper and I can't believe that I flopped it in june lol
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    Right I will be permanent on this thread in the next 7 hours :_)
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    Hopefully finalise the extra information I need tomorrow, then from saturday onwards, past papers
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    (Original post by mathsclown)
    Hopefully finalise the extra information I need tomorrow, then from saturday onwards, past papers
    Awesome.My sleeping pattern is messed up for now but anyhow.. I did past papers on genetics ages ago.Few were tricky but loved them <3
    So yea tonight I will finished biotech and stuff... leaving ecostuff,animal plant behavior (easy) and animal psychobiology (bah).
    What topics have you got to finish now ?
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    (Original post by ibysaiyan)
    Awesome.My sleeping pattern is messed up for now but anyhow.. I did past papers on genetics ages ago.Few were tricky but loved them <3
    So yea tonight I will finished biotech and stuff... leaving ecostuff,animal plant behavior (easy) and animal psychobiology (bah).
    What topics have you got to finish now ?
    Nice! Hmm just little minor things now, the timber production bit, commercial use of plants and nitrogen cycle, then should be fine
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    (Original post by mathsclown)
    Nice! Hmm just little minor things now, the timber production bit, commercial use of plants and nitrogen cycle, then should be fine
    Hmm timber YEA that caught me off guard back in june.. nitrogen cycle is fun :P
    nitrosomonas,denitrfication.A week left! :P
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    (Original post by ibysaiyan)
    Hmm timber YEA that caught me off guard back in june.. nitrogen cycle is fun :P
    nitrosomonas,denitrfication.A week left! :P
    Yup not long too go :s hoping for a nice paper, even though most of it is logic !
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    Could you guys throw me some F215 questions please?
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    (Original post by Summerdays)
    Could you guys throw me some F215 questions please?
    Sure: Describe meiosis in detail =]
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    (Original post by ibysaiyan)
    Sure: Describe meiosis in detail =]
    Interphase - Each pair of chromosomes uncoil and replicate.

    Prophase 1 - The chromasomes shorten and thicken. The centrioles move to opposite end of the cell, forming spindle fibres. The nuclear membrane disintegrates. The homologous chromasomes pair up. As they pair up they can form chiasma/chiasmata between non-sister chromatids from the homologou pairs. This enables crosing-over to occure (when bit of DNA are transfered from one non-sister chromatid to another.)

    Metaphase 1 - The homologous pairs line up across the equator (via random assortment.) The centromeres of the chromosomes are attached to the spindle fibre. The non-sister chromatids are held together via chiasmata.

    Anaphase 1- The spindle fibre shorten, pulling the homologous pairs to seperate poles of the cells.

    Telophase 1- Nuclear membrane reforms and chromosome lengthen and become thinner. The cell split forming two daugter cells via cytokinesis.

    Prophase 2 - Chromosomes shorten and thicken. Nuclear membrane disintegrates, Centrioles move to opposite ends of the cell, forming spindle fibres.

    Metaphase 2- Chromosomes line up around the equator (via random assortment) of the cells and attach their centromeres on the spindle fibres.

    Anaphase 2 - spindles fibre shortens, pulling appart the chromatids that were attached to the centromeres in the chromosome to opposite pole of the cell.

    Telophase 2- Nuclear membrane reforms in each daughter cell. Chromatid lengthen and become thinner. The two cells each split into two daughter cells via cytokinesis to produce a total of four daughter cell.

    (This was done via memory.)

    BTW, don't ask me anything from module four yet, as I have forgotten a lot of it and need to revise them ^^
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    Anymore questions?
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    (Original post by Summerdays)
    Anymore questions?
    I knew them already hmm.. anyways how's your revision going? have you done any past papers ?tonight I will try to finish most of the modules leaving animal/plant behavior and co-ordination :P

    One thing which upsets me is that in the book it says most of the enzymes/penicillin is made by fed batch culture BUT practically Penicillin is made by continuous.So which should one go for lol..
 
 
 
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