DNA replication in vivo

Question 1

in the cell, what is the primer?

Answer 1

RNA

Question 2

DNA polymerase properties

Answer 2

reads template sequence and links nucleotides

reads 3’ to 5’ and synthesizes new DNA 5’ to 3’

MUST always start from on existing 3’ OH end of an existing template

Question 3

semi conservativeness of dna replication

Answer 3

one strand from parent one new

Question 4

function of helicase

Answer 4

breaks hydrogen bonds between base pairs and unwinds the DNA double helix

Question 5

function of primase

Answer 5

synthsizes RNA primers on DNA leading and lagging strands

Question 6

function of DNA pol. I

Answer 6

replaces RNA primers with DNA nucleotides

Question 7

DNA ligase

Answer 7

catalyzes phosphodiester bond formation, joining DNA fragments on lagging strand

Question 8

function of topoisomerase

Answer 8

relaxes supercoiled DNA

Question 9

SSBPs

Answer 9

coat single stranded DNA

Question 10

DNA Pol. III

Answer 10

synthesizes DNA 5’ to 3’ on leading and lagging strands

Question 11

the leading strand has what ‘ end of the strand pointing to/ at the replication fork

Answer 11

the 3’ end, because bases are added from 5’ to 3’ therefore can be added directly as the dna unwinds

Question 12

how many replication forks are there in one replication bubble

Answer 12

2

Question 13

where is the origin of replication located and how many are there in 1 replication bubble

Answer 13

right in the middle of the middle of the bubble, like at the top of a bridge, there is one origin or replication for each bubble which is where replication in both directions begins

Question 14

replication with circular DNA

Answer 14

generally only one origin of replication (generally called OriC)

replicates in a circle, engds generally meet up

Question 15

replication with linear DNA

Answer 15

can begin at any origin of replication , eukaryotes have many many

more than one origin or replication (gen called OriR)

when 2 replication forms meet they fuse to form one large bubble

Question 16

process of separating the DNA strands

Answer 16

topoisomerase relives stress of unwinding, while helicase unwinds, single-strand binding protein (SSB) stabalizes the single strands of DNa

Question 17

process of making primers for DNA replication

Answer 17

DNA poly req a primer sequence so it can add to a 3’OH group, RNA primase synthesizes an RNA primer which DNA polymerase can extend

Question 18

what creates the RNA primers

Answer 18

the enzyme primase

Question 19

fragments of dna on lagging strand

Answer 19

okazaki fragments

Question 20

leading vs lagging strand

Answer 20

leading strand has 3’ end facing towards replication fork therefore can continuously grow (located on DNA template strand w/ 5’ end at fork)

lagging strand has 5’ end towards for, therefore must be synthesized in small fragments (okazaki fragments) which are joined by dna ligase which catalyzes formation of phosphodiester bonds to join the fragments. before ligase links the fragments, DNA polymerase 1 must replace the RNA primers with DNA