AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

can anyone explain restriction mapping to me please

Restriction mapping is used in order to sequence the bases of a certain sample. It is accomplished by cutting the DNA with different restriction endonucleases and seperating the resultant DNA fragments using gel electrophoresis. Once the size of the fragments are known a restriction map can be made showing the restriction endonuclease recognition sites and the order of fragments.

Then DNA Probes can be used to find specific genes.

Can you not open the rar file? Have you got winrar downloaded onto your laptop/computer?
I will only be able to send it as a rar file because otherwise its too big to send. Download winrar. Locate the file and extract it.

Well i'll tell you the true chain of events, also what you're describing is "transcription", which is transcribing of DNA into pre-mRna then into mRna after splicing. Translation comes later with the use of ribosomes and the formation of a polypeptide. But anyway:

1) DNA Helicase attaches to the start of the gene being transcribed at the start codon, and goes down the gene breaking the hydrogen bonds until it reaches the stop codon.

2) RNA polymerase moves down the now exposed bases (DNA template, refer to semi-conservative replication in AS biology) and causes exposed bases to join with complementary RNA molecules in the nucleoplasm and a strand of pre-mRNA is now formed.

3) The pre-mRNA is then spliced where the introns in the base sequence is removed, and the exons are joined together. The exons can join together in a variety of combinations resulting in multiple polypeptides being coded for by the same gene.

So in short, the revision guide is correct. What textbook is that out of interest? That seems like a pretty basic and rather alarming error.

this paper looks scary, can you guys tell me if a2 is hard? the essay questions in particular i don't look forward to, im in AS right now just finished my unit 1 and unit 2 aqa biology, im hoping for an A in AS but will A2 be hard to get an A in?

Biology is . If you are good at applying your knowledge to crazy, never seen before situations that AQA examiners like to think of then you should be fine.

I'm hoping to do Pharmacy this year Organic chemistry

My college has finsihed everything so we are revising 'Synoptic Biology' as it comes up in the essay and in the papers! Biol5 is going to be a tough paper especially with the 25 mark synoptic essay but its not that bad as it can only be on some certain topics (about 10 from AS + A2). Try to do every past essay question and get it marked form your teacher. I started off getting 17/25 and I'm now on 22/25. You get better with practice!

I am glad i got an A in bio4 the first time round, that unit was easily the dullest thing i've ever done, unit 5 is far more interesting, even if the synoptic essay is a right ol' pain.

Can anyone explain transcription factors to me please? I fear the book has missed some bits out that are important to their role/s, and all the websites I've looked at have a little too much on them. Would love a middle ground between the two to help me understand how they work.

Also the diagram is pretty damn wierd/**** in the Mark Thorne book =/

Thanks in advance.

I know what you mean, I got 136/140 in Biol4 so i am so so so relieved it just takes off so much pressure, but I agree biol5 is soooooooo much more interesting!

BIOL4 is out of 100 UMS

Can you not open the rar file? Have you got winrar downloaded onto your laptop/computer?
I will only be able to send it as a rar file because otherwise its too big to send. Download winrar. Locate the file and extract it.

hi , sorry to bother you but have u got any questions for biol4 like u had for biol5 . im retaking biol4..

Well i'll tell you the true chain of events, also what you're describing is "transcription", which is transcribing of DNA into pre-mRna then into mRna after splicing. Translation comes later with the use of ribosomes and the formation of a polypeptide. But anyway:

1) DNA Helicase attaches to the start of the gene being transcribed at the start codon, and goes down the gene breaking the hydrogen bonds until it reaches the stop codon.

2) RNA polymerase moves down the now exposed bases (DNA template, refer to semi-conservative replication in AS biology) and causes exposed bases to join with complementary RNA molecules in the nucleoplasm and a strand of pre-mRNA is now formed.

3) The pre-mRNA is then spliced where the introns in the base sequence is removed, and the exons are joined together. The exons can join together in a variety of combinations resulting in multiple polypeptides being coded for by the same gene.

So in short, the revision guide is correct. What textbook is that out of interest? That seems like a pretty basic and rather alarming error.

And also RNA polymerase makes a copy of which strand? anti - sense or sense? and why?