DNA Metabolism, Sequencing, and PCR Flashcards
Does RNA polymerase need a primer?
No
Proofreading is mediated by?
3’ to 5’ exonuclease activity
DNA helicase activity induces?
Positive supercoils
How many origins of replication are found in bacterial DNA?
One
Activation of origin of replication in eukaryotes is dependent on?
Cell cycle
What is the role of reverse transcriptase from retroviruses?
Make double stranded DNA from RNA
What is the role of telomerase in reverse transcriptase?
Add telomeric repeats protecting the chromosome from degradation
Most common replication errors are?
Mismatches and changes in number of short tandem repeats
What is the cellular response to UV damage?
Nucleotide excision repair
What is the role of exinucleases and endonucleases?
Make cut “nick” in single stand at the two sites flanking the damaged bases in nucleotide excision repair
DNA polymerase delta and epsilon function to?
Fill in the gap left by exinuclease
DNA lipase functions to?
Make phosphodiester bond between newly synthesized DNA and flanking DNA strand
What is the cause of cockayne syndrome?
Ineffective recognition of stalled RNA polymerase
What is the main external and endogenous cause of double stranded breaks in DNA?
X-Rays are external, stalled replication forks over improperly resolved DNA damage sites
Base excision repair starts with removal of damaged base by?
Glycosidase
What carries out translation at the nick in DNA done by endonucleases after glycosidase has removed damaged base?
DNA polymerase I
What proteins recognize mismatches in DNA and initiate mismatch repair?
MutS and MutL
What cuts the newly synthesized strand at the hemimethylated GATC site?
MutH
After large portion up to the mismatch is removed by helicase/exonuclease action, the gap is then filled in by?
DNA polymerase III
What part of the cell cycle does nucleotide excision repair take place?
G1
What part of the cell cycle does mismatch repair take place?
G2
CpG dint leotards are underrepresented in human genome, why?
Because C in this dinucleotide is easily methylated and mutated to T, this can lead to complimentary G being replaced by mismatch repair yielding a mutation. Hence why these dinucleotides are mutation hotspots
For PCR-amplification of mRNA or viral RNA, mRNA must first be?
Reverse transcribed to DNA
Does DNA polymerase need a primer?
Yes
