OCR 2010 A2 Biology Unit 2 - Control, Genome and Environment

Dude you're on a different level.

Could you expand on the Founder effect, I get the idea but I can't explain it consicely.

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! :/

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.

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?

Guys.....I didnt see genetic drift in the spec? is this that synoptic ****?

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

can anyone explain the Mutations with beneficial and harmful effects:

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?

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?

explain, with examples, how environmental factors can act as stabilising or evolutionary forces of natural selection;

Help.

It's in the spec, it's among that section that I dislike

Just read your profile. Got bored. You keep changing your sig picture. lol

can anyone explain the explain how the genes control development of body plans and stuff on the homobx gene thingy bob.

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...