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Mar_Ryan_block2_mm10 DNA Replication (elongation (many proteins are…
Mar_Ryan_block2_mm10
DNA Replication
elongation
lagging strand goes in 5' direction
several DNA polymerases work together to produce
lagging strand
okazaki fragments replicate the rest of the DNA that is upstream of the ori
leading strand goes in 3' direction
replication is continuous
carried out by a single DNA polymerase
replication goes in both ways (bidirectional)
many proteins are utilized to correctly
perform DNA replication
gyrase stabilizes the uncoiled DNA to prevent supercoiling
DNA pol 1 replaces RNA primers with DNA
primase adds RNA primer to the parent template so DNA Pol III can polymerize the daughter strand
DNA ligase joins adjacent okazaki fragments.
Helicase unwinds and unzips the DNA double-helix
DNA pol 2 looks for and corrects any errors
DNA pol 3 elongates the DNA from the RNA primers
intiation
DNA A (protein) attaches to
9mer to initiate replication
DNA A causes oscillation at the 13mer site
This is because 13mer site is weaker
than the 9mer site, so it is easier to
oscillate and form a bubble
it is weaker because of the presence
of many AT pairs, since AT has weaker bonds
than GC
begins at ori (origin of replication)
ori is the region between the 13mer and 9mer
SSB proteins attach to the bubble
to stabilize it and prevent it from closing up
DNA B proteins come in to begin unwinding and
unzipping the DNA for elongation
termination
when replication is done, uncoded regions (Telomeres) are left at the ends of the strand so to protect said strand
any damage would be applied to the telomere,
not the coding region
over time, telomeres get shorter (via many many replications), and eventually the coding region will become damaged
this damage is what usually leads to cancer, and/or disease,
and is why we are more prone to cancer as we age
in some cases, ter sites (termination sites) are used
they ensure that both leading and lagging strands are
finished at the same time
it is regulated by the Tus protein
both strands would meet at one ter site, and replication would be done