Difference between DNA replication and transcription

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Please could someone explain question 5 in the paper In January 2007
Link is below ...
http://pastpapers.org/AS/biology/foundation/2007_Jan_2801.pdf

Posted Sat 28th April, 2012 @ 18:18 by M.Ahmed

1 Answer

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DNA Replication - The Steps:

  • the double helix untwists
  • the DNA "unzips" exposing the bases
  • free nucleotides hydrogen bond onto the exposed bases according to the base pair ruling ( A-T and C-G)
  • covalent bonds form between a sugar of one nucleotide and the phospate of another.

In DNA replication it happens all the way along the molecule so two replicas are formed which are identical to the origional. This is called semi-conservative replication.

DNA Transcription:

This is when a small part of the DNA becomes exposed (the DNA coding strand). Free RNA nucleotides hydrogen bond to the DNA to form a complementary strand. However the base pairings are slightly different. C-G are the same but U bonds with A. then the sugar phosphate backbone seals up. This short strand is then read by the ribosomes to produce proteins.

Hope this helps answer the question. If not, then say and i try to explain ones you aren't sure on.

Sophie

Answered Sun 29th April, 2012 @ 14:41 by Sophie