Some of the DNA replication enzymes:
1.
2.
Topoisomerase- unwind DNA helix structure (change DNA topography);
DnaA protein
opens replication origin to form replication bubble;
DNA – helicasebreak H-bonds between base pairs;
this creates a replication fork;
Y-shaped structure;
with single stranded DNA section;
3.
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4.
DNA polymerase IIIfor polymerisation in prokaryote
Delta DNA polymerase:
for polymerisation in eukaryote
5.
NB: 4 & 5 above also proof read a nucleotide they just
added
6.
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7.
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8.
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9.
10.
Leading strand;
daughter strand continuously made towards
a growing replication fork;
because 3’  5’ direction of reading parent
template is towards the growing Replication fork;
so its synthesised just behind the leading strand
Lagging strand;
daughter strand discontinuously made in
opposite direction of a growing replication fork;
- because 3’  5’ direction of reading the parent template
- is away from the growing Replication fork;
Okazaki fragments;
several short DNA strands;
joined to primers;
growing away from replication fork;
later join to make the daughter DNA lagging strand;
DNA Primase; - add short RNA nucleotides called RNA primers;
RNA primers; - short RNA nucleotide used to make double strand &
provide initial 3’ C- OH for polymerising DNA polymerase like 5 & 5 above to start work;
DNA polymerase I – remove of RNA primers then replace them with DNA nucleotides;
11.
12.
DNA ligase- join DNA fragments like Okazaki fragments to form the continuous DNA strand;