TEST 3 DNA Replication

Question 1

What are the three fundamental rules of DNA replication?

Answer 1

Semiconservative Bidirectional Proceeds 5’ to 3’ semi-discontinuously.

Question 2

What is semiconservative?

Answer 2

Each strand serves as a template for a new strand.

Question 3

Bidirectional means what?

Answer 3

DNA replication is initiated at the origin of replication. Replication then spreads in both directions from these points.

Question 4

What is meant by proceeds 5’ to 3’ semi discontinuously?

Answer 4

Synthesis is always 5’ -> 3’

Question 5

Role of AAA+ ATPase

Answer 5

Disassociates DNA strands at origin of replication, using energy from ATP.

Question 6

Role of DNA ligase

Answer 6

Seals nicks in the phosphodiester bonds

Question 7

Role of DNA polymerase?

Answer 7

Hooks nucleotides together to elongate the strand.

Question 8

Role of Helicase?

Answer 8

Present at the fork and works to unwind the fork.

Question 9

Role of Endonuclease?

Answer 9

Cleaves the phosphodiester bonds between nucleotides inside the DNA strand.

Question 10

Role of Exonuclease

Answer 10

Cleaves the phosphodiester bonds between nucleotides at the end of the DNA strand.

Question 11

Role of Primase?

Answer 11

Lays down the RNA primer that DNA polymerase needs to start

Question 12

Role of Topoisomerase?

Answer 12

Alleviates supercoiling stress.

Question 13

What is required for DNA polymerase to function?

Answer 13

A template and a primer.

Question 14

DNA poly 3 role?

Answer 14

Synthesizes most of the DNA

Question 15

DNA poly 1 role?

Answer 15

Involved in DNA repair and removal of RNA primers

Question 16

DNA poly 2,4,5?

Answer 16

Involved in DNA repair.

Question 17

Steps of DNA replication?

Answer 17

Initiation - Melting of the DNA at origins of replication Elongation - Leading and lagging strand synthesis. Termination - halting of polymerases and resolving catenated chromosomes.

Question 18

What is the only regulated phase of DNA replication?

Answer 18

Initiation

Question 19

5’ - 3’ Polymerase activity

Answer 19

Synthesizes DNA

Question 20

5’ - 3’ Exonuclease activity?

Answer 20

Removes primers

Question 21

3’ - 5’ Exonuclease activity?

Answer 21

“Proofreading”

Question 22

What are the three levels of control in DNA replication?

Answer 22

Geometry, Proofreading, and mismatch repair system.

Question 23

Differences between Prokaryotic and Eukaryotic DNA replication?

Answer 23

• Eukaryotic:
  
  • Much slower than prokaryotic
  • Multiple origins of replication
    
    • These origins are AT rich
  • Telomere replication is different
  • Nonmenclature is in Greek letters not roman numerals.

Question 24

Polymerase alpha role?

Answer 24

Contains primase, initiates DNA synthesis.

Question 25

Pol B role?

Answer 25

Repair

Question 26

Poly gamma role?

Answer 26

Replicates mitochondrial DNA

Question 27

Pol epsilon role?

Answer 27

Elongate the leading strand

Question 28

Pol delta role?

Answer 28

Elongate okazaki fragments

Question 29

How do eukaryotic cells protect their DNA from reacting during replication?

Answer 29

They are capped with Telomeres

Question 30

What happens when the telomeres disappear?

Answer 30

Cellular Sensescence G0 state

Stops replicating.

Question 31

What is cellular crisis?

Answer 31

Low levels of telomers, and is pushed to divide anyway.

Results in chromosomal fusion events, cancer, normally the cells die.

Question 32

Where is telomerase found?

Answer 32

Stem cells

Question 33

What is heteroplasmy?

Answer 33

Different cells in the body can have different mitochondrial genomes/

Question 34

Where is the gene that replicates mitochondria found?

Answer 34

In nuclear DNA

Question 35

Describe Mitochondrial depletion syndromes?

Answer 35

Often occur in eyes, liver, or neurons (all are high energy)

DNA that codes for mitochondrial replication is lost and thus more cannot be made.

Question 36

Examples of Mitochondrial disease?

Answer 36

Alpers syndrome

Progressive external ophthalmoplegia

Ataxia-neuropathy syndrome.