AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

Woo, more people from xaverian? ^_^


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yesssssssssssssssssssssssssssssssssssssss badass dont think i know of her, ive seen the tall one though! and the kick boxer or thai boxer or something like that

oh and could you explain the part of translation where 'all the codons have been read and a polypeptide is produced' ?? confused...

Transcription:
- Occurs in the nucleus
- DNA stands are split by hydrogen bonds being broken by DNA helicase
- One of the strands acts as a template
- Individual RNA nucleotides align next to the template according to specific base pairing
- The difference being uracil replaces thymine
- RNA nucleotides are joined together by RNA polymerase
- This creates a strand of pre-MRNA which undergoes splicing (removes introns and joins together exons) and leaves through a nuclear pore to the cytoplasm to attach to a ribosome to undergo translation.

Translation:
- Occurs in a ribosomes in the cytoplasm
-Sequence of codons on mRNA is used to determine the sequence of amino acids in a polypeptide and works by:

- Each tRNA molecule has 3 exposed bases called an anti-codon.
- tRNA with the anticodon complimentary to the first mRNA codon will move towards the mRNA strand bringing along the specific amino acid
- Other tRNA join in order determined by mRNA
- Amino acids join together by peptide bonds which require ATP.
- tRNA then begins to move away, leaving behind the amino acids. It collects another amino acid of the same kind so it can be reused.
- This continues until all codons have been read and it reaches a stop codon, and a specific polypeptide is then produced from the sequence of amino acids.
- The polypeptide then folds into secondary/tertiary structures.

FEel free to ask more if something doesnt make sense

Yeah its basically the other one thats young, thats not the ones you mentioned ahaha :')



Basically like... when all the codons have been read by tRNA and matched to an amino acid

hey can you please explain the oestrous cycle and the positive an dnegative factors in that please

I know, which is annoying as I do geography Are you prepared for it?

so all the amino acids that join for the polypeptide? :s
i've only had mr simpson and garnzzzz! best teachers around though

Not fully, I'll spend a lot of tomorrow doing essay prep I think, but I'm feeling ok about the main exam, been getting decent A's so far but the essay could mess it all up :/


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I had miss chadwick last year (the tall one) and she was really good!

But yeah So when it gets to the end of the mRNA strand, all of the codons have been read, so therefore all the amino acids will have been brought over by tRNA and joined together to create a polypeptide

the tall one thank you i get all confused with a gene codes for this and dna codes for this and this forms a polypeptide and this forms a gene and the bases codefor this and this codes for that :| is there a simple way of remembering that?

Same :/ I still need to go over the synoptic stuff I did my first essay on cause of disease the other day and got 18/25 which is alright i suppose, but I am not hugely confident on things like negative feedback :/ That's really good! but yes, this is AQA we are talking about :L

Haha too right...I'll also look at some of the mark schemes for essays and see what they're looking for


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