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Steps of DNA
replication
1. DNA helicase
(enzyme) unwinds the DNA. The junction between the unwound part
and the open part is called a replication fork.
2. DNA polymerase
adds the complementary nucleotides and binds the sugars and phosphates.
DNA polymerase travels from the 3' to the 5' end.
3. DNA polymerase
adds complementary nucleotides on the other side of the ladder.
Traveling in the opposite direction.
4. One side
is the leading strand - it follows the helicase as it unwinds.
5. The other
side is the lagging strand - its moving away from the helicase
Problem: it
reaches the replication fork, but the helicase is moving in the
opposite direction. It stops, and another polymerase binds farther
down the chain.
This process
creates several fragments, called Okazaki Fragments, that
are bound together by DNA ligase.
6. During replication,
there are many points along the DNA that are synthesized at the
same time (multiple replication forks). It would take forever to
go from one end to the other, it is more efficient to open up several
points at one time.
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