DNA replication and manipulation Flashcards
Where does DNA replication occur
S phase
What shape is DNA in
helix w two antiparallel strands
Why do hydrogen bonding inbetween DNA strands allow it to unravel
bc they are weaker
What direction is DNA made
5’-3’ only
DNA replication conservative model
no mixing DNA
Semiconservative model
evenly split mixed DNA
Dispersive model
random mixing DNA
Which experiment showed that DNA replication is semi-conservative
messelsohn and stahl
How did messelsohn and stahl do their experiment
growing bacteria in lighter and lighter nitrogens and DNA forms bands when centrifuged
Draw out semiconservative model
Dark strand on first, split half on second, and light and half on third
If DNA replication was conservative which bands would be observed after one round of replication
heavy and light
Complications in DNA replication(4)
- unwinding tension
- only add nucleotides to existing nucleotide
- opposite directions on each strand
- pieces need to be joined together
Helicase
unwinds double helix at replication forks
Single-strand binding protein
binds and stabilizes single stranded DNA when it is used as a template
topoisomerase
relieves strain of overwinding by breaking, swiveling, and rejoining DNA strands