three theories of replication
conservative, semi conservative, dispersive
meselson and stahls experiment showed what?
semi conservative was true
bacteria is what and what? and has how many origins?
small and circular. 1
types of bacteria replication
rolling-circle, theta replication
eukaryotic is what and what? with how many origins?
large and linear. numerous
theta replication unidirectional or bidirectional?
both
product of theta replication?
two circular DNA molecules
rolling circle replication unidirectional or bidirectional?
unidirectional
replication in rolling circle is initiated by what?
break in one of the nucleotide strands
DNA synthesis begins at what end? and which end is displaced?
3’, 5’
products of rolling circle?
multiple circular DNA molecules
what are the products of eukaryotic replication
two linear DNA molecules
new DNA is synthesized from what?
dNTP’s. deoxyribonucleoside triphophate
what forms between two necleotides
phosphodiester bonds
nucleoside=?
base and sugar
DNA synthesis is mediated by large enzymes called?
DNA polymerase
DNA polymerase are dependent on what?
primers
what are primers
short strands of DNA or RNA with free 3’ OH groups
DNA polymerases do what?
add nucleotides one at a time to the free 3’ OH
DNA elongation in what direction?
5’-3’
which strand moves with the replication fork?
leading strand
which strand moves away from the fork
lagging
discontinuous strand
lagging
continuous strand
leading
okazaki fragments
lagging
leading requires how many primers?
1 at the origin
lagging requires how many primers?
multiple at beginning of fragment
RNA primers have to replaced by what? what does this? then what is need to fill in gap?
DNA, polymerase 1. DNA ligase
leading and lagging strands are in what two processes?
theta replication and eukaryotic replication
leading and lagging not in what process?
rolling circle
four stages of replication
initiation, unwinding, elongation, termination
what binds to the replication origin?
initiator proteins
initiator proteins cause what?
DNA segment to unwind and form replication bubble
helicase does what
breaks hydrogen bonds between strands of DNA
helicase bind to what?
lagging strand template
how does helicase move along replication fork?
along it in 5’-3’
single strand binding proteins do what?
stabalize the single stranded DNA during replcation. keeps it from re coiling
DNA gyrase is considered a what?
topoisomerase
DNA gyrase does what?
reduces re coiling
primase does what
syntheses short RNA primer with the 3’ OH group and placed the primer in the orgin
elongation or adding of nucleotides requires what?
3’ OH group
what removes RNA primers and fills in the gap?
polymerase 1
what is the major replication enzyme?
polymerase3
which polymerase are involved with DNA repair
2,4,5
which polymerase have exonuclease in the 3’-5’
1,2,3
exonucleases:
remove a nucleotide only from the end of a chain
enconuclease
break bonds within a chain
enzyme that catalyzes the synthesis of DNA by using template strand
polymerase 3
enzyme that replaces all RNA primers used to initiate elongation
polymerase1
what has 5’-3’ exonuclease activity?
polymerase 1
what fills in the last nick? and how
ligae. catalyzes phosphodiester bonds
primase add what
primer
termination can occur in two ways
when two forks meet, or TUS which blocks helicase and stalls fork
during eukaryotic replication what is needed for initation
multi protein recognition complex (ORC)
ORC does what
initiates unwinding of DNA
as replication fork moves away what happens to eh licensing factor?
it is removed
3 types of polymerase in eukaryotic replication
alpha, delta, epsilon
which polymerase completes lagging strand?
delta
which polymerase complete leading strand
epsilon
alpha polymerase does what
initiates both leading and laggin strand . synthesize RNA primer and a short segment of DNA nucleotides (30-40)
why can primers at the end of chromosomes not be replaced
there is no adjacent 3’OH group that nucleotides can be attatched
ends are called what
telomere
gap is left by what
removal of last RNA primer
enzyme that aids in the completion of replication?
telomerase
telomerase is what two things?
protein RNA hybrid molecule