DNA Replication (Lecture 12) Flashcards
What does it mean that DNA synthesis is semi-discontinuous?
lagging strand replicates discontinuously while lagging strand is continuous
What are the 4 universal rules for DNA replication that viruses need to adhere to?
need DNA (3’-5’) template, need a free 3’OH end, synthesis occurs 5’-3’, replication occurs only at Ori’s, need accessory proteins such as helicase, always primer dependent
What are the 4 obstacles that DNA viruses face when it comes to DNA synthesis?
DNA polymerase not always present, no telomeres on their genome but need to replicate their whole genome, replication machinery only recognizes eukaryotic DNA, at least one viral protein is used SO DNA replication is postponed until viral protein is made
What are the 4 essential genes/proteins for DNA viruses?
DNA polymerase and accessory proteins, origin of binding protein and helicase, endonucleases, enzymes needed for nucleic acid metabolism (synthesis) which host cells do not have
What do TRL and TRS stand for?
terminal repeats long and short
What do IRS and IRL stand for?
internal repeats short and long
What are the 2 ways that dsDNA can be replicated?
replication fork synthesis and strand displacement
What is replication fork synthesis?
replication occurs on BOTH strands and uses RNA primer
What is strand displacement synthesis?
replication only occurs on one strand while other strand is displaced, uses a DNA primer OR a protein primer (ie: serine)
With SV40 viruses (dsDNA), what is the first biosynthetic event?
synthesis of LT viral protein
What is the LT viral protein?
has helicase activity, recognizes Ori and binds to it
What type of DNA replication do parvovirus undertake? What do they use as a primer?
continuous and DNA
What is the viral protein that parvovirus need for DNA replication and what is its function?
Rep78/68, viral endonuclease
What is the purpose of Rep78/68?
creates a new free 3’OH
What is pTP?
viral protein used by adenoviruses as a primer
What type of DNA replication do adenoviruses undertake?
strand displacement with no end problem
What is rolling circle replication and which viruses perform this kind of method?
continuous DNA synthesis
What are the 2 required to carry out the rolling circle replication?
endonuclease to put a nick in the DNA and DNA polymerase
What is a concatemer? And how is it packaged into progeny virions?
identical genomes that are connected but will be cut into seprate genomes during packaging and will be packaged each into a new virion
What are the 2 obstacles for DNA viruses? And the solutions (if any) to these obstacles?
lack of telomeres (solved with concatemers) and DNA polymerase as it is not always presemt inside the cell
What is the protein that regulates the START checkpoint’?
Rb protein
What is the start checkpoint of the cell cycle?
checks if the cell has grown enough with enough proteins and nutrients to undergo cell division?
What happens once you pass the start checkpoint?
cell is commited to cell divison, either it will divide or undergo apoptosis
What is the Rb protein? What is it’s role?
holds onto E2F and keeps it until it is phosphorylated and releases E2F
How do viruses make DNA polymerase available?
viruses target Rb protein by making a viral protein that can bind to Rb so that it releases E2F
What is E2F and what is its role?
a transcription factor that binds to DNA and turns on gene expression
