Sunday 22 February 2015
Quote of the Day #1
"Science and everyday life cannot and should not be separated." -Rosalind Franklin
The 3 Acts of DNA Replication
Initiation:
Elongation:
Termination:
- Helicase unwinds and separates DNA (at the point of origin)
- Binding proteins bind to keep the DNA strands apart and unwound
- Gyrase enzyme cuts the DNA to release the tension
- Primase makes an RNA primer which the DNA polymerase III uses to begin replicating the new strands
Elongation:
- Polymerase III adds nucleotides to the 3' of the new strand
- DNA's anti parallel structure results in the new strands growing in opposite directions
- Leading vs Lagging strands:
- the leading strand replicates continuously
- the lagging strand replicates discontinuously
- RNA primase synthesis RNA primer
- Polymerase III extends the strand by adding new nucleotides to the 3' end
- a new DNA fragment is generated from the end of each primer
- the DNA fragments are called Okazaki fragments
- Polymerase I removes RNA primer and fills the gap by extending the neighbouring DNA
- Okazaki fragments are joined by DNA Ligase
Termination:
- Newly formed strands rewind
- Replication machine dismantles as the new DNA molecules separate from each other and the DNA replication is complete
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