DNA replication and repair -- Lecture 6 Flashcards
direction of DNA replication:
5’ –> 3’
DNA Pol III needs a ___ to attach a new nucleotide to
3’-OH
___ needs a 3’-OH to attach a new nucleotide to a new strand of DNA
DNA Pol III
is DNA Pol III able to add the first nucleotide in DNA replication?
NO
what begins the DNA replication?
primase
primase (what is it and what it does)
doesn’t have limitation that DNA Pol III has
a type of RNA polymerase
begins the DNA replication process
DNA replication:
new RNA nucleotides are added to leading strand ___ by primase
faster
DNA replication:
new RNA nucleotides are added to lagging strand ___ by primase
slower
how to remove the RNA?
DNA polymerase I removes and replaces the RNA nucleotides w/ DNA nucleotides
removal of RNA:
___ removes and replaces RNA nucleotides w/ DNA nucleotides
DNA polymerase I
DNA polymerase I ___ the RNA nucleotides w/ DNA nucleotides
removes and replaces
DNA Polymerase I removes and replaces the ___ w/ ___
RNA nucleotides w/ DNA nucleotides
RNA removal and nick repair:
“nicks”
missing phosphodiester bonds
RNA removal and nick repair:
missing phosphodiester bonds
nicks
RNA removal and nick repair:
DNA Pol I (does what)
1) removes the RNA nucleotides
2) replaces them w/ DNA nucleotides
3) can’t form the last phosphodiester bond, leaving a ‘nick’ in the DNA backbone
RNA removal and nick repair:
DNA Ligase (does what)
1) enzyme that restores the missing phosphodiester bonds that DNA Pol I leaves behind –> “nick repair”
RNA removal and nick repair:
Okazaki fragments
fragments of the duplications in the lagging strand that are being converted from RNA to DNA
DNA polymerase processivity:
DNA polymerases are enzymes w/ high ___
processivity
DNA polymerase processivity:
___ are enzymes w/ high processivity
DNA polymerases
DNA polymerase processivity:
DNA polymerases are ___ w/ high processivity
enzymes
DNA polymerase processivity:
DNA polymerases can add ___ w/o falling off of the DNA (very stable)
thousands of nucleotides
DNA polymerase processivity:
DNA polymerases can add thousands of nucleotides w/o ___ (very stable)
falling off of the DNA
DNA polymerase processivity:
DNA polymerases can add thousands of nucleotides w/o falling off of the DNA (___)
very stable
DNA polymerase processivity:
___ can add thousands of nucleotides w/o falling off of the DNA (very stable)
DNA polymerases
DNA polymerase processivity:
why are DNA polymerases so stable?
a protein called “sliding clamp protein” stabilizes the interaction b/n DNA polymerases and the DNA
DNA polymerase processivity:
“sliding clamp protein” (what does it do)
stabilizes the interaction b/n DNA polymerase and the DNA
what happens when there is a mistake in DNA replication?
if DNA polymerase adds an incorrect nucleotide, it can replace it w/ the correct nucleotide
what happens when there is a mistake in DNA replication?
if DNA polymerase adds an ___, it can replace it w/ the ___
incorrect nucleotide
correct nucleotide
what happens when there is a mistake in DNA replication?
if ___ adds an incorrect nucleotide, it can replace it w/ the correct nucleotide
DNA polymerase
what happens when there is a mistake in DNA replication?
DNA polymerase has a ___ function
proofreading function
what happens when there is a mistake in DNA replication?
___ has a proofreading function
DNA polymerase
DNA repair enzymes:
DNA repair enzymes ___ DNA damage
find and repair
DNA repair enzymes:
___ find and replace DNA damage
DNA repair enzymes
DNA repair enzymes:
DNA repair enzymes find and replace ___
DNA damage
DNA repair enzymes:
excision repair enzymes ___ mismatches and DNA damage (e.g. thymidine dimers)
detect and repair
DNA repair enzymes:
excision repair enzymes detect and repair ___ (e.g. thymidine dimers)
mismatches and DNA damage
DNA repair enzymes:
___ detect and repair DNA damage (e.g. thymidine dimers)
excision repair enzymes
DNA repair enzymes:
our DNA repairing enzymes are constantly at work repairing our DNA (true/false)
true
deficiencies in DNA repair enzymes:
xeroderma pigmentosum (XP) – what is it
rare genetic disorder of DNA repair enzymes
deficiencies in DNA repair enzymes:
in XP patients, excision repair enzymes have a significantly reduced ability to ___
repair DNA damage
deficiencies in DNA repair enzymes:
in XP patients, excision repair enzymes have a ___ ability to repair DNA damage
significantly reduced
deficiences in DNA repair enzymes:
Xeroderma pigmentosum leads to…
___% of patients die before 20
development of cancers frequently and at a young age
60%
deficiencies in DNA repair enzymes:
ER enzymes are ___
critical for survival
deficiencies in DNA repair enzymes:
___ are critical for survival
ER enzymes
