Flashcards in DNA Replication LO Deck (48)
what does semi-conservative mean?
Newly replicated DNA has one parental strand and one daughter strand
what does bidirectional mean?
replication begins at a site of origin and simultaneously moves out in both directions from this point
how many sites of origin do prokaryotes have?
how many sites of origin do eukaryotes have?
What is a replication fork?
site at which DNA synthesis is occurring
what do origin binding proteins do?
recognize and bind onto origins of replication
what types of nucleotides are origins of replication rich in?
A and T
what do helicases do?
unwinds DNA ahead of the replication fork by breaking hydrogen bonds between strands
what do single-strand binding proteins do?
bind to each single strand of DNA and hold it in single stranded conformation
What do topoisomerases do?
prevent extreme supercoiling of parental helix that would result as a consequence of unwinding at replication fork
how do topoisomerases prevent supercoiling?
break and rejoin DNA strands
what is important about DNA gyrase in prokaryotes?
can be inhibited by quinolones in treatment of disease
which direction does DNA synthesis proceed?
5' - 3'
how does DNA polymerase work?
adds deoxyribonucleotides to the 3' hydroxyls of RNA primers and subsequently to ends of growing DNA strands
what does a primase do?
catalyzes the addition of RNA primer to begin replication
what are the 2 types of DNA polymerases in prokaryotes?
DNA pol I and DNA pol III
what is the major replicative enzyme for DNA and why?
DNA pol III because it has a sliding clamp that keeps it attached to the DNA template
what does DNA pol I do?
mediates replacement of RNA primers with DNA
through which 3 processes does DNA pol I work?
a. 5' - 3' exonuclease activity for RNA primer removal
b. 3' - 5' exonuclease activity for proofreading
c. 5' - 3' DNA polymerase activity
what is the function of DNA Pol III
it is the major replicative enzyme in DNA synthesis
why is DNA pol III the major replicative enzyme?
because it has a sliding clamp which keeps it attached to the DNA over a long distance
what are the 3 DNA polymerases in eukaryotes?
Pol α Pol δ and Pol ε
what is the function of DNA pol α?
synthesizes the first 20 DNA nucleotides after the RNA primer
what types of activity are located in DNA pol α? (2)
primase activity and DNA polymerase activity
NO PROOF READING
which polymerase performs lagging strand synthesis in eukaryotes?
which polymerase performs leading strand synthesis?
what serves as the primer for DNA polymerase in cells?
what enzyme places the RNA primer?
what is the classification of primase?
DNA-dependent RNA polymerase