2 DNA Replication Flashcards
what do a-helices have to do with protein interaction with DNA?
they can fit into the major groove and interact with the nitrogenous bases
when an ORC recognizes an origin site, what happens first?
unzipping of DNA via helicase, establishment of rep fork
what class of protein is T-Ag?
helicase
is helicase ATp dependent?
yes
what are the three major proteins needed to initiate replicaiton?
- helicase (T-ag)
- Humans single stranded binding protein (replication protein A)
- topoisomerase 1
what is the function of SSB (RPA)?
required for replication, stabiliizes single stranded DNA
what is the cause of blooms disease and what are these patients at risk for?
- deficient in helicase
- risk for malignancies
what is the cause of werners syndrome? what are the symptoms?
- gene involved is a helicase
- premature aging, dwarfism, cataracts, scleroderma
what polymerase initiates DNA synthesis? how does it do so?
Pol alpha makes RNA/DNA primers
what polymerase synthesizes the lagging strand? what is this dependent on?
pol delta, PCNA (proliferating cell nuclear antigen) (clamp) dependent
what polymerase synthesizes the leading strand?
pol epsilon, PCNA dependent
what type of reaction occurs as nucleotides are added to the DNA chain?
nucleophilic attack, creating a phosphodiester bond
what is RF-C’s job in DNA synthesis?
this is a clamp loader, it is responsible for secruing PCNA which then recruits the pol delta or epsilon
the pieces of DNA that are synthesized piece meal on the lagging strand are called what?
okazaki fragments
what direction exonuclease activity does pol e and d have?
3’ to 5’ because it goes backwards to do this
what is necessary to join okazaki fragments?
DNA ligase