Unit 02.1: DNA Replication Flashcards
(35 cards)
what is the function of the DnaA enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
it recognizes the initiation of DNA replication by binding to DnaA boxes, as well as the A-T rich.
analogous to ORC
what is the function of the DnaB helicase enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
called in by the binding of DnaA to DnaA boxes, unwinds on both ends of the replication fork!
analogous to MCM2-7 helicase
what is the function of the gyrase enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
makes cuts in supercoils that are produced while DNA is uncoiling and then glues the cuts back together.
analogous to topoisomerases.
what is the function of the single stranded binding proteins in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
stabilizes DNA strands so that they do not reanneal.
analogous to replication protein A (RPA)
what is the function of the primase enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
lays down RNA primers so DNA Polymerase 3 has something to extend off of.
analogous to DNA-pol primase complex
what is the function of the DNA Polymerase 3 enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
it extends the DNA from RNA primers on 3’ end.
analogous to DNA Pol ε for the leading strand and DNA Pol σ for the lagging strand
what is the function of the DNA Polymerase 1 enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
proofreads DNA and removes RNA primer, replacing it with DNA by excising RNA nucleotides
analogous to FEN1 (for removing the primers) and DNA Pol ε (for replacing RNA with DNA)
what is the function of the ligase enzyme in prokaryotic DNA replication? which eukaryotic enzyme is it analogous to?
seals loose ends between okazaki fragments of lagging strand by gluing final phosphodiester bond between nucleotides together.
analogous to DNA ligase 1.
what is the function of ORC in eukaryotic DNA replication? which prokaryotic enzyme is it analogous to?
initiates replication by recognizing and binding to a sequence downstream an A-T rich segment. it then binds cdc6 and 2 helicase + cdt1 complexes
analogous to DnaA
what is the function of MCM2-7 helicase in eukaryotic DNA replication? which prokaryotic enzyme is it analogous to?
unwinds DNA helix after cdt1 and cdc6 proteins dissociate, sliding creating replication bubble and sliding towards replication forks, unwinding as it goes.
analogous to DnaB helicase.
what is the function of cdc6 in eukaryotic DNA replication?
assisting with the binding of helicase
what is the function of topoisomerases in eukaryotic DNA replication? which prokaryotic enzyme is it analogous to?
to relieve tension by making cuts!
analogous to gyrase
what is the function of DNA Pol ε and DNA Pol σ in eukaryotic DNA replication? which prokaryotic enzyme is it analogous to?
to add nucleotides onto leading and lagging strand respectively.
analogous to DNA Pol III
what is the function of telomerase in eukaryotic DNA replication?
extends telomeres in gametes where one strand of DNA is longer than other
describe the steps of telomere extension.
- telomerase anneals to 3’ overhang on mRNA
- RNA acts as template to add bases onto DNA
- DNA nucleotides are then translocated (moved further away)
- elongation of other strand that didnt have nucleotides translocated
- DNA polymerase fills gap on the first strand
which enzymes have 3’ to 5’ exonuclease activity?
DNA Pol 1 and 3
how fast does the replication fork move?
1000 bp/sec
how many bp are there per full turn of the double helix?
10 bp
what is the error rate in DNA Replication?
<1 error / every 10^10 nucleotides
where is the T-loop? what is its function?
a knotted loop found in telomeres which protects the telomeres from enzymatic degradation by joining with a protein complex called shelterin
what is the hayflick limit?
the number of replication cycles in a cells life span (50-70)
how many origins of replication do prokaryotes have vs eukaryotes?
pro - 1
eu - manyyyy
why does eukaryotic DNA not replicate into an identical copy as prokaryotic DNA does?
bc eukaryotic DNA is linear and cannot fully replicate due to the RNA primers at the end of the DNA which DNA Pol cannot add onto bc 3’ end not available
each new nucleotide is added onto which end of the previous one?
3’
