F215 - Revision thread 13th June 2011

Selective breeding and evolution by natural selection both change the allele frequencies in the next generation, so the alleles that code for the beneficial or desirable characteristic will be passed on to offspring and become more common in the next generation. If a random mutation produces an allele that is beneficial or desirable, it will be selected for it the next generation, either because it increases the organism's chance of survival, or because it is useful to humans.

However, in natural selection, the organisms that reproduce are selected for by the environment, whereas in selective breeding this is carried out by humans. Natural selection gives an unpredictable result, but artificial selection aims for predetermined results. Natural selection makes the species better adapted to the environment therefore increasing it's chances of survival, reproduction, and passing on the advantageous allele to the next generation. Artificial selection however, does not benefit the organism, it just makes it more useful to humans.

It's not very detailed :/ Do you think that's okay?

ahh i see, aww im sure u will go up! and it will be good revision for this course seeing as its synaptic? synoptic...or whatever the word is that means they can test us on previously learnt things! have you alraedy done the resit?

Yeah it's pretty detailed included most of the terms needed in markscheme to

Haha yayy thank you

would you like another?

whats the definition for transcription factors?

whats the definition for transcription factors?

what exactly do you mean? the unwinding and unzipping.....

Yes please if you don't mind haha

do we not need to know the definition for transcription factors?

whats the definition for transcription factors?

Right guys seriuosly Im so stressed. My dad has been ill lately and I havent been able to find time to revise beause of course family comes first. And anyway the bulk of revison I was going to do tonight and tomorrow as just gone out of the window and found outsome bad news. Anyone got any idea if I can get some consideration? My lifes a mess atm

explain how knowledge of particular genes can be used in the filed of modern medicine? 4 marks
outline the formation of recombinant DNA? 3 marks

Just did Jan '11...What the hell was with that comparing PCR to in vivo or whatever one. Got 0/8 for that



Thankfully grade boundaries were super low

ahh not sure what to talk about exactly in this one, i tend to just write everything i can think of in exams so i think i'd say this:
Gene therapy could be used to cure genetic disorders e.g. cystic fibrosis. It involves altering alleles in body cells, particularly those that are most affected by the disorder. Gene therapy could prolong the lives of people with genetics disorders and give them a better quality of life
DNA probes can be used to identify DNA fragments that contain specific sequences of bases. For example, they can be used to locate genes on chromosomes or see if a person’s DNA contains a mutated gene that causes a genetic disorder.



The DNA fragment containing the desired gene is isolated using restriction enzymes. The DNA fragment is inserted into vector DNA. The vector DNA is cut open using the same restriction enzyme that was used to isolate the DNA fragment, so the sticky ends of the vector are complementary to those of the fragment. The vector DNA and DNA fragment are mixed together with DNA ligase, which joins them by their sugar-phosphate backbones. The new combination of bases in the DNA (vector DNA and DNA fragment) is called recombinant DNA.

Not sure about that one either

Does anyone think auxins will come up?
I'm thinking if they do, they could link it to the plant transport topic in AS because auxins move via phloem over long distances? I really hope they don't

Has anyone else got a summary about the homeobox not sure if what I know about it is sufficient?