L5 DNA REPLICATION

Question 1

what is an s strain?

Answer 1

a virulent bacterial strain with a protective capsule

Question 2

what is an r strain

Answer 2

rough without a protective capsule and is non virulent

Question 3

what is the transforming principle?

Answer 3

a subtance in the heat killed s cells caused a hertible change of non virulent R bacteria into virulent s bacteria

Question 4

what is cell divison?

Answer 4

genome duplication

Question 5

regulation of replication in prokaryotes

Answer 5

linked to nutrient availability

Question 6

regulation of replication in prokaryotes

Answer 6

regulated by the cell cycle

happens in s phase

Question 7

de novo mutations?

Answer 7

mutation that appears for the first time

Question 8

In the Meselson and Stahl experiment, if DNA replication had been
conservative, after one round of replication they would have observed

Answer 8

2 bands, one heavy and one lights

Question 9

dan semiconservative replication

Answer 9

a double helix duplicates so that each new double helix contains:

1 parental strand
1 newly synthezied strand

Question 10

what is antiparallel orientaton

Answer 10

One strand runs 5’ → 3’

The complementary strand runs 3’ → 5

Question 11

what direction is the leading strand duplicated in?

Answer 11

5’ → 3’ direction. continous synthesis

Question 12

what direction is the lagging strand duplicated in?

Answer 12

Discontinuous synthesis, producing Okazaki fragments in the 5’ → 3’ direction

Question 13

what are okazaki fragments joined by?

Answer 13

dna ligase

Question 14

what does the ‘bidirectional’ movement of dna replication mean?

Answer 14

dna duplication proceeds in both directions away from the origin of replication (starting point)

Question 15

replication fork

Answer 15

both template strands are replicated at each replication fork

Question 16

why is dna semi-discontinuous?

Answer 16

The leading strand is synthesized continuously

The lagging strand is synthesized discontinuously (okazaki fragments

Question 17

what is dna polymerase?

Answer 17

catalyze the polmerization of deoxynucleotides

Question 18

what is the function of dna polmerase?

Answer 18

dna replication + maintenance

Question 19

what direction are nucleotides added?

Answer 19

to the free 3’ –OH of the growing strand

Question 20

newly syntehized dna is,,,,

Answer 20

complementary and anitparallel

Question 21

what is primase?

Answer 21

an rna polymerase

Question 22

primer removal and replacment

Answer 22

primers are later removed by nucleases that recognize rna’dna hybrids

Question 23

what does dna ligase do?

Answer 23

seals the final mick to create a continuous strand

Question 24

origin of replication (prokaryotes)

Answer 24

ONE region of replication (oriC)

Question 25

origin of replication (eukaryotes)

Answer 25

multiple origins of replication per chromosome

Question 26

G1 phase

Answer 26

Origin of replication complex, inactive helicase

Question 27

S phase

Answer 27

dna unwinds and replication proteins recruited to initiation dna syntheis

Question 28

what direction does the leading strand replicate? (continuous)

Answer 28

smae direction as the replication fork, one primer

Question 29

what direction does the lagging strand replicate? (discontinuous)

Answer 29

away from the replication fork in okazaki fragments, multipule primers

Question 30

what do single-strand binding proteins do?

Answer 30

bind to single-stranded dna after helix is unwound to prevent reannealing, degradation, and keep the strand extended

Question 31

Quick integration with replication steps:

Answer 31

Helicase unwinds DNA → ssDNA exposed. SSB proteins bind immediately → stabilize ssDNA. Primase and DNA polymerase then carry out synthesis.

Question 32

What does primase do?

Answer 32

synthesizes RNA primer and elongated by DNA polymerase

Question 33

What role does primase play in DNA replication

Answer 33

Primase synthesizes the RNA primer needed to initiate synthesis of Okazaki fragments.

Question 34

what does dna helicase do?

Answer 34

unwinds the double helix at the front of the replication fork atp dependant

Question 35

what do topoisomerases do?

Answer 35

relieve stress forming dna nicks/breaks swivles to allow dna to rotatate during replication

Question 36

topo type 1

Answer 36

single strand cuts

Question 37

topo type 2

Answer 37

double strand cuts

Question 38

sliding clamp and clamp loader?

Answer 38

cooridnate dna unwinding and syntehsis

Question 39

Telomerase

Answer 39

A specialized reverse transcriptase enzyme. Extends telomeres using an RNA template. Prevents loss of essential DNA sequences at chromosome ends.

Question 40

what is dna polymerase?

Answer 40

enzymes that replicate and repair dna with the help of accessory proteins

Question 41

proofreading in dna

Answer 41

dna polymerase edits incorrect inccorporated nucleotides

Question 42

Telomerases are necessary in eukaryotes because:

Answer 42

Eukaryotic DNA polymerases cannot copy all the way to the end of a chromosome

Question 43

what is fidelity?

Answer 43

faithful copy of dna parental dna template

Question 44

Proofreading

Answer 44

3’→5’ exonuclease activity

Question 45

DNA polymerases in eukaryotes do not function to

Answer 45

Extend telomeres