DNA Replication In Prokaryotes

Question 1

In which phase of mitosis does replication occur

Answer 1

Synthesis

Question 2

DNA replication is semi conservative. This means?

Answer 2

One of parents strands serves as template to form other strand. Observed from Messelson and Stahl Experiment

Question 3

In Meselson and Stahl experiment, bacteria are cultured for how many generations

Answer 3

20. In N15 first. Then N 14

Question 4

In cairns experiment bacterial cells are labelled with

Answer 4

3-H thymidine

Question 5

What is the replication fork?

Answer 5

Proteins and enzymes needed for DNA replication assembled at origin of replication

Question 6

Replisome

Answer 6

:All proteins and enzymes needed for replication

Question 7

Replicative helicase has how many subunits

Answer 7

6

Question 8

Function of DNA Polymerase

Answer 8

Polymerizqtion of deoxyribonucleotides. Elongation of daughter stand

Question 9

Helicase

Answer 9

Unwinds DNA

Question 10

Primase

Answer 10

Synthesises RNA primer

Question 11

Topoisomerases

Answer 11

Relieve overwinding ahead of replication fork and decatenate the final product

Relieves torsional strain from helicase induced winding

Question 12

Single strand binding protein

Answer 12

Stops single strand(lagging) from folding into secondary structure

Question 13

Y clamp complex loader

Answer 13

Loads beta sliding clamp on leading and lagging strand

Question 14

B sliding clamp

Answer 14

increases progressivity of dNA polymerase. Without it polymerase would fall off

Question 15

Ligase

Answer 15

Seals nick between okazaki fragment and okazaki fragment

Question 16

Synthesis on lagging strand is semi discontinuous. What does this mean and why does it occur

Answer 16

It means does synthesis occurs in bits because synthesis occurs opposite the direction of the replication fork.

Question 17

What is the byproduct of polymerase adding dntps

Answer 17

Piphosphate

Question 18

Which ligase joins okazaki fragments

Answer 18

DNA ligase 1

Question 19

Properties common to all DNA polymerased

Answer 19

Catalyse the polymerisation of deoxyribonuvleotides in the 5’ to 3’ direction
Require a template
Require a primer

Question 20

What is the difference between DNA polymerase 1 and 3

Answer 20

DNA polymerase 1 is responsible for replacing RNA primers with DNA by nick translation

DNA polymerase III is the main replicase

Question 21

What are the other subunits of the DNA polymerase holoenzyme

Answer 21

Y complex, B subunit, T subunit(holds two polymerase 3 cores together)

Question 22

DNA Polymerase I was discovered in … by …

Answer 22

Late 50s, by A Kornberg

Question 23

How long aree okazaki fragements

Answer 23

1000 to 2000 base pairs long