Monday, February 27, 2012

The story of replication, transcription and translation.


Replication
Transcription
Translation





Initiation

- helicase
- single stranded binding protein keep template strands apart
- gyrase releases tension from the unwinding DNA
- primase (A to U, C to G)


- All in the initiation complex found in the promoter region
- transcription factors (proteins)
- TATA box on DNA
- RNA II (protein and template)


- tRNA, mRNA, the first amino acid and two ribosomal subunits are brought together
- MET, the start codon
- read 5’ AUG 3’











Elongation









- DNA polymerase III elongates from 5’ to 3’ and reads 3’ to 5’






- Known as the Transcription Unit
- RNA polymerase II reads DNA 3’ to 5’, ultimately creating RNA 5’ to 3’ that is similar to the coding strand


- read mRNA from 5’ to 3’
- codon recognition occurs at the A-site with the bonding of mRNA with the anticodon
- peptide bond formation with amino acids from A site and polypeptide at P site
- ribosome move tRNA with polypeptide from A to P site for translocation.


Termination

- DNA polymerase I proofreads and replaces RNA primers with DNA nucleotides
- ligase ‘glues’ the gaps


- AAUAAA sequence (RNA) stops the production of RNA
- pre mRNA is created


- stops upon reaching a stop codon: UAA, UAG, UGA

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