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DNA: Semi-conservative
By Adesewa Alade…read more

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What is DNA Semi-
conservative Replication?
· DNA replication requires the concerted
action of a number of proteins. the
proteins involved are clustered
together in replication factory within
the cell nucleus.
· The DNA to be copied is fed through
the proteins of the replication factory.
· The duplex DNA to be copied is first
split into single strands. Each of the
two template strand is copied and
becomes half of a new DNA double-…read more

Slide 3

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Objective…read more

Slide 4

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The Proteins…read more

Slide 5

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What are their Functions?
Helicase is made of six proteins arranged in a ring
shape unwinds the DNA double helix into 2
individual exposed complimentary strands.
· Single Strand Binding Proteins (SSBs) coat each
strand of DNA preventing the DNA strands from
reannealing (forming back into a double helix again).
· Primase is a RNA polymerase that creates short RNA
primers needed to start of the replication process.
· DNA polymerase is an enzyme that strings up free
nucleotides and in the process extends the DNA
· The sliding clamp helps hold the polymerase onto
each strand of the DNA during replication.
· RNase H removes the RNA primers that were
previously attached during the DNA strand
synthesis.…read more

Slide 6

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Extra Parts
A replication fork is an area where DNA
separates into two strands and a new DNA
synthesis occurs. It is the area where the
parental strands are copied to create two
A double strands.
daughter helix consist of two anti parallel
DNA strands, 3 or 5 complimentary strands
running in opposite orientation.
The RNA polymerase only extends nucleic
acid chain and cannot begin from scratch
so the Primase synthesizes RNA primers
(up to 60 nucleotides long) as a guide to
help each polymerase go in opposite
orientation when one bumps into a primer it
stops, leaving a gap, forming okasaki
Before the lagging strand leaves the
replication factory in the nucleus the
primers need to be removed and the two
okasaki fragments can be joined together,
which is when the RNase H comes in,
Then the DNAthe primers by hydrolysing
ligase connect their
the 3 okasaki
fragment end to bonds.
the 5 okasaki fragment
end to form one complete DNA strand in a…read more

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