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    (Original post by Sakujo)
    Dude you're on a different level. :laugh:

    Could you expand on the Founder effect, I get the idea but I can't explain it consicely.
    A founder effect occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have:

    *reduced genetic variation from the original population.
    *a non-random sample of the genes in the original population.

    Any clear ? If not quote me back .Thanks
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    (Original post by ibysaiyan)
    Wow 5 marks? lets see If I remember a fraction. Ok
    Genetic drift is simply change in the allele frequency number which is caused by randomness(Un-related to recombination,natural selection or mutation).In some cases it increases the net. hybrid allele in others it depreciates them.The rise of the new allele could be give the specie advantage over the rest of the individuals such that over the period of time its population increases this change in pattern is your genetic drift.
    For example, consider what would happen if ... wildflower population ... consisted of only 25 plants. Assume that 16 of the plants have the genotype AA for flower color, 8 are Aa, and only 1 is aa. Now imagine that three of the plants are accidently destroyed by a rock slide before they have a chance to reproduce. By chance, all three plants lost from the population could be AA individuals. The event would alter the relative frequency of the two alleles for flower color in subsequent generations. This is a case of microevolution caused by genetic drift..
    There are two types of driftage:
    Bottleneck effect : Is caused by natural processes such as earthquake,flood and fire reducing the variety level.
    Founder effect: Here a small group goes onto a different path and forms a different population.
    Arghh... 8 exams to go! :/
    Ah Thanks. Love you isybaiyan! How did your exams go?
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    THank you also sakujo.
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    (Original post by ViolinGirl)
    DNA replication is making copies of a DNA molecule. 2 DNA molecules are produced. The DNA to be replicated unwinds and unzips, the hydrogen bonds between the complementary bases break by action of DNA helicase enzymes. Free nucleotides present within the nucleus will bind to the complementary molecules on the DNA template strand to reform the DNA molecule. Hydrogen bonds reform by action of enzyme DNA polymerase. The semi-conservative theory refers to the fact that each DNA molecule now consisits of one orginal strand and one new strand, that are used to form the double helix molecule.

    Translation is the second stage of protein synthesis, whereby the amino acids are assembled to make polypeptides, and this sequence is dictated by the codons on the mRNA coding strand that fits into the ribosomal subunits. In translation the mRNA will fit into the ribosomal groove, and 2 codons with be exposed to the larger subunit. The first exposed codon is always AUG, so a tRNA molecule with an amino acid bearing the code for methionone attached to this via the anticodon. Another tRNA bearing a different amino acid binds to the second codon, and a peptide bond is formed betweeen the 2 amino acids. The process continues, with each tRNA then leaving the mRNA molecule to pick up more amino acids until a stop codon is reached that indicates the amino acid chain is complete.
    Ahhh just found it, its all AS!!! Thank u! Damn all these synoptic links gotta go revise AS soon. Has anyone else started on it? I've barely begun A2!!
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    (Original post by ibysaiyan)
    A founder effect occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have:

    *reduced genetic variation from the original population.
    *a non-random sample of the genes in the original population.

    Any clear ? If not quote me back .Thanks
    So is the founder effect just genetic drift in small populations?

    I thought it was more to do with increased likelyhood of isolation/selection pressures of different individuals of population leading to speciation? :erm:
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    can anyone explain the Mutations with beneficial and harmful effects:
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    (Original post by Sakujo)
    So is the founder effect just genetic drift in small populations?

    I thought it was more to do with increased likelyhood of isolation/selection pressures of different individuals of population leading to speciation? :erm:
    It is! The bottleneck effect refers to situations where the population undergos a rapid change in size e.g a tree falling on a population of worms and killing a large proportion of worms holding one type of allele, perhaps for length.
    The founder effect is where a small population becomes isolated from another, and this leads to speciation.
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    Guys.....I didnt see genetic drift in the spec? is this that synoptic ****?
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    (Original post by The TSR Star.)
    Guys.....I didnt see genetic drift in the spec? is this that synoptic ****?
    It's in the spec, it's among that section that I dislike :shifty:

    explain how genetic drift can cause large changes in small populations;
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    (Original post by Jacker956)
    can anyone explain the Mutations with beneficial and harmful effects:
    These are in particular mutations that can have different effects dependant on the environmental conditions, so in one situation they can be beneficial and in other situations they will be harmful. One example is this is that of skin colour in humans. Early humans in Africa were known to have dark skin, this protected them from the harmful effects of UV light and allowed for enough vitamin D to be synthesised due to the intense sunlight on their skin. Humans who had inherited an allele that gave them paler skin were at a disadvantge, because they would burn and lead to problems like skin cancer.
    However, due to migration, in regions of less intense climates, people with the allele for paler skin are at an advantage, because they are still able to sythesise vitamin D, even though the sunlight is not as intense as it was before, but people with an allele for darker skin will not be able to synthesis vitamin D, and this can lead to a number of health issues, including increased risk of Heart disease.

    Other mutations will either be beneficial or harmful. E.g. Cystic fibrosis, here the transmembrane chloride ion channels are altered and as a result chloride and water cannot be transported across membranes lining reproductive tracts and airways. Cilia wil not be hydrated and cannot shift mucus, so this will lead to infections, other problems associated with CF include infertility.

    Mutations with beneficial effects may be those such as an alteration in colour that results in better camouflage, e.g. with peppered moths. This mutation becomes the favoured allele within the population, as it gives a greater chance of survival, and is selected for by nat. seletion.
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    (Original post by ViolinGirl)
    Ah Thanks. Love you isybaiyan! How did your exams go?
    Ah no problem yea they went great with exception of one anyways don't want to give it much thought as I have further eight to handle with =} How about you?
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    (Original post by ibysaiyan)
    Ah no problem yea they went great with exception of one anyways don't want to give it much thought as I have further eight to handle with =} How about you?
    Glad to here it! Ah. I haven't had any as of yet. Just panicking about physics really. I think I'll have my revision sorted for the other 3 subjects in time. just physics...
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    (Original post by ibysaiyan)
    Ah no problem yea they went great with exception of one anyways don't want to give it much thought as I have further eight to handle with =} How about you?
    Just read your profile. Got bored. You keep changing your sig picture. lol
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    explain, with examples, how environmental factors can act as stabilising or evolutionary forces of natural selection;
    Help.
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    (Original post by Sakujo)
    Help.
    Environmental factors can act as stabalising or evoltutionary forces of natural selection...

    The size of a population will be governed by environmental factors. With most poulations they will continue to expand until they reach their carrying capacity (the maximum size of the population that the environment can sustain). Some of the environmental factors that determine this carrying capacity include space, availability of water, food, nitrates, light, predation and disease. These are both abiotic and biotic factors.

    Selection pressure is where an environmental factor gives an advatage to certain members of a population allowing them to survive to reproductive age. E.g. If it is snowing in the habitat then white rabbits have an advantage to survive and as a result they will be the ones to survive to pass of favourable alleles, but if the snow suddenly melted, then this environmental factor is altering the direction of natural selection. This is a directional change, and acts as an evolutionary force. Because now, grey rabbits are more likely to survive.

    Environmental factors also offer environmental resistance. Populations tend to be fairly stable-this is due to environmental factors. If the environmental reisitance of one factor becomes great enough e.g. water availability then the population will decline, and there will then be less intraspecific competetion and it will gradually rise again, untill there results in more intraspecific competion so remains fairly stable again. This acts as a stabalising force.
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    (Original post by Sakujo)
    It's in the spec, it's among that section that I dislike :shifty:
    hahaha i totally forgot about that section. Who wants a bet the entire exam will be on utter crap such as that very section?
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    can anyone explain the explain how the genes control development of body plans and stuff on the homobx gene thingy bob.
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    (Original post by ViolinGirl)
    Just read your profile. Got bored. You keep changing your sig picture. lol
    Ah yea... :/ well yea me and my profile are best buds 4eva ! lol :/ blame it to 0% experience in social life.
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    (Original post by Jacker956)
    can anyone explain the explain how the genes control development of body plans and stuff on the homobx gene thingy bob.
    Hey bob sup =} Oh sure let give it a go:
    Homebox genes code for the basic structural formation(body plan) of the organism i.e from zygote to a whole organism.
    These genes are function the same in any organism (argh cant think remember the exact word which I am looking for starts from "p") in nature.These work by coding for transcription factor proteins which attach onto their respective places in the DNA.These allows certain part to get transcribed hence you get the resulting changes.
    Some genes of these kind are: Antp and ubx.Where ubx codes for the inhibition of the growth of wings in the T3 segment.
    While the Antp codes for the formation of 3 pairs of leg in each Body segment.
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    (Original post by ViolinGirl)
    Glad to here it! Ah. I haven't had any as of yet. Just panicking about physics really. I think I'll have my revision sorted for the other 3 subjects in time. just physics...
    Yea physics arghh the last module of WJEC is just full of unwanted, repetitive info -.- seriously .... you have 5.5 and 5.6 dedicated to particle accelerators,x-rays,heart pumping, Doppler usage in blood :lolwut: and what not also on top of all that a 20 mark question (yes 20) totally synoptic based ....... on LHC <_<
 
 
 
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