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4. Primase is actually part of an
aggregate of proteins called the
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primeosome.
This enzyme attaches a small RNA primer to the
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single‑stranded
DNA to act as a substitute 3'OH for DNA polymerase
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to
begin synthesizing from. This RNA primer is eventually removed
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by RNase
H and the gap is filled in by DNA polymerase I.
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5. Ligase can catalyze the formation
of a phosphodiester bond given
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an
unattached but adjacent 3'OH and 5'phosphate. This can fill in the
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unattached
gap left when the RNA primer is removed and filled in.
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The
DNA polymerase can organize the bond on the 5' end of the
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primer,
but ligase is needed to make the bond on the 3' end.
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6. Single‑stranded binding proteins
are important to maintain the
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stability
of the replication fork. Single‑stranded DNA is very labile, or
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unstable,
so these proteins bind to it while it remains single straded and
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keep it from
being degraded.
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