DNA replication (A-level stuff) I am so DUMB!

by - 03:00

DNA strands
- antiparallel (5' to 3' strands run in opposite direction)
- complementary
- synthesis of DNA takes place at 3' prime end!
- daughter DNA (semi conservative) - consist of one paternal strand and one new dna strand

1. Helicase unwinds DNA strand and break the H bond in between the bases
2. SSBP (single strand binding protein) - prevents DNA strands from reannealing
3. RNA primer attaches and copies first stretch of strand.
4. DNA polymerase starts polymerization by adding free nucletides to the strand by complementary base pairing.
TWO polymerase is needed, one for each strand and they start synthesising from 5' to 3' end! One of the strand is copied continuously whereas on the second strand the polymerase copies until it runs into previous primer, so it has to repeatedly release itself and slide further upstream to start copying from another Primer! This forms OZAZAKI Fragments (short stretch of DNA making the lagging strand)

5. RNAase H removes RNA primer after copying is complete
6. Lagging strand is joined up by enzyme called ligase.

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