DNA Replication/Repair 2 Flashcards Preview

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Flashcards in DNA Replication/Repair 2 Deck (15):
1

What are DNA gyrases (Topoisomerases ) for?

They nick DNA to loosen (negative supercoil) DNA strands


It’s necessary for Helicase to do its job

2

Fluoroquinolones inhibit the following enzymes in prokaryotes ?

1. Topoisomerases II and IV

3

In Eukaryotes, Topoisomerase I is inhabited by the following agents?

1. Irinotecan
2. Topotecan

4

In Eukaryotes, Topoisomerase II is inhabited by the following agents?

1. Etoposide
2. Teniposide

5

How is the Telomere involved in cellular aging ?

1. It’s the end portion of the chromosomes
2. Has repetitive sequences
3. DNA polymerase can’t keep up with synthesis
4. Telomere gets shorter
5. Cell dies
6. Prevented by telomerase activity

6

What is Telomerase for?

1. Aids in DNA synthesis of the Telomeres
2. It’s a reverse transcriptase (RNA dependent DNA polymerase )
2. Goes haywire with tumors

7

What is reverse transcriptase ?

1. Synthesizes DNA from RNA (reverse).
2. Present in many viruses in order to add their genome into the host’s
3. Inhibited by AZT

8

What is the main cause of Thymine dimers?

UV radiation

9

Enzyme necessary to remove Thymine Dimers?

1. Excision endonuclease

10

Tumor suppression genes that regular G1 entry into S phase ?

1. p53
2. Rb

11

What happens in cytosine deamination?

1. Cytosine looses amino group—>
Uracil

12

Excision enzyme for Cytosine deamination ?

Uracil Glycosylase Endonuclease

13

Enzyme absent in Xeroderma pigmentosum ?

Excision endonuclease

14

Damage to this DNA repair mechanism causes Lynch Syndrome ?

DNA mismatch repair

15

How are RNA primers replaced to DNA in Eukaryotes?

1. Polymerase delta