W3 DNA replication Flashcards
where do chromosomes replicate from
origin of replication
what makes a region an origin of replication
high amounts of A and T
which direction does the replication fork go
5’ to 3’
which strand is in the 5’ to 3’ direction
leading strand
what are lagging strand fragments called
okazaki strands
how is supercoiling undone
by topoisomerase
why must RNA primers be removed off okazaki fragments
so there are no RNA left
when a flap is made on the okazaki fragment how is it removed
by FEN1
how is the RNA primer degraded
ribonuclease H
how does circular chromosome replicate
- initiator proteins start at origin of replication
- helix is opened and then helicase binds
- loading proteins detach
why cant we fully replicate lagging strand
no upstream RNA primer
what is the telomere and its function
repeating nucleotides which can loop to prevent unwanted DNA repair
whats the role of the PCNA complex
improve speed of DNA replication
what chemical process activates DNA replication in the S phase
phosphorylation
what happens to histones during replication
recycled in the s phase
Name the 5 proteins at the replication fork
helicase
SSBPs
DNA polymerase
RNA primers
ligase
why do cells need a replication limit
- less mutations
- no loss of DNA
what can stain DNA
ethidium bromide and UV light
how can PCR measure gene expression
measure the amount of cDNA reverse transcribed
what are the main roles of Pol-α + Pol-δ + and Pol-ε
Pol-α synthesises primers
Pol-δ works on the lagging strand
Pol-ε synthesises the leading strand
what are the steps for PCR
heat to 95 to remove H bonds
cool to 50 to anneal primers
heat to 72 for taq polymerase to extend
why might active telomerase be harmful
Can lead to cancer
what is needed for electrophoresis
TAE buffer
agarose gel
how is recombinant DNA created
cut plasmids with restriction enzymes
ligate sticky ends
What does qPCR measure
Gene expression levels based on UV
