17 dna replication 1 Flashcards
(28 cards)
the enzyme that causes the 5’->3’ addition of the correct base
DNA polymerase III (prokaryotic)
what fuels dNTP addition?
2 phosphate groups
DNA polymerase 1 has what kind of activity?
5’ exonuclease
these things cut DNA into large pieces within the strand
endonucleases
DNA polymerase III and dna polymerase I have what kind of activity?
3’ exonuclease
the three functions of DNA polymerase III?
- tests that the base is correct. 2. synthesizes a phosphodiester bond. 3. proofreading with 3’ exonuclease
explain the polymerase activity of dna pol III
5’->3’, processive with beta clamp, fast, needs RNA primer to start
explain the 3’ exonuclease activity of DNA pol III
cuts nucleotides at 3’ end, super-vigilant proofreader. LOW mutation rate
gyrase is also known as what?
topoisomerase II
helicase does what?
breaks H bonds
primase does what?
makes primers
what is the sliding clamp composed of and how wide is it?
two beta subunits, 35angstroms
two fun facts about replication:
it is semiconservative and bidirectional
okazaki fragments require what before they are synthesized?
RNA primer
which direction does the leading strand grow in?
TOWARDS the replication fork
which direction does the lagging strand grow in?
AWAY from the replication fork
the primosome is composed of what?
helicase and primase
what enzyme stabilises the single strands?
single stranded binding proteins
this enzyme removes the RNA primer and fills the gaps
DNA polymerase I
this enzyme joins the individual okazaki fragments together with a phosphodiester bond
DNA ligase
what enzyme is the primase and what does it do?
RNA polymerase. it can synthesize de novo strands. NO 3’ exonuclease function, removed and replaces w/dna. RIBOSE, easy to identify
function of DNA pol 1 in the cell
primer filling, DNA repair
function of DNA pol III in the cell
DNA replication
nucleotides/sec for Pol I
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