DNA Replication and Transcription

Question 1

DNA Topoisomerase function

Answer 1

Changes the tertiary structure of DNA – introduces ssqivel points in order to correct supercoiling and allow DNA to continue transcription.

Question 2

DNA Helicase function in replication

Answer 2

Catalyzes DNA strand separation for replication– uses ATP to force strands apart at the replication fork.

Question 3

DNA polymerase: which way can it synthesize?

Answer 3

Only in the 5’–>3’. Meaning, that it reads the template strand in the 3’–>5’ direction toward the replication fork.

For the lagging strand this is done in fragments

Question 4

DNA Polymerase a

Answer 4

Primer synthesis, no exonuclease activity. Starts synthesis on the leading and lagging strands.

Question 5

DNA Polymerase d

Answer 5

Replication on the lagging strand

Has 3’»5’ exonuclease activity - removes primers.

Question 6

DNA Polymerase E

Answer 6

DNA replication o f the leading strand , with 3’»5’ exonuclease activity.

Question 7

Exonuclease function MMR

Answer 7

Removes DNA from incisions around the mismatched nucleases

Question 8

Exonuclease activity in BER

Answer 8

Lyase activity – removes phosphate and sugar.

Question 9

Endonuclease in MMR

Answer 9

Makes incisions

Question 10

Endonuclease in BER

Answer 10

Cleaves backbone

Question 11

Endonuclease in NER

Answer 11

Makes incisions at 5’ and 3’ ends of the lesion.

Question 12

Ligase

Answer 12

Seals gaps created by repair mechanisms.

Question 13

Base Excision Repair function

Answer 13

Excises damaged/modified bases.

Question 14

Nucleotide Excision Repair general function

Answer 14

Removal of bulky adducts and lesions to the DNA.

Question 15

Global Genomic NER

Answer 15

performed on DNA not in the active transcription state.

Question 16

Transcription Coupled NER

Answer 16

Performed on DNA that is being actively transcribed.

Question 17

Mismatch Repair function

Answer 17

Replaces mismatched but NOT DAMAGED nucleotides, insertions, deletions.

Question 18

Double Strand Break Repair function

Answer 18

Fixes breaks on both strands of DNA.

Question 19

Single strand break repair function

Answer 19

Fixes breaks in 1 strand of DNA from OXIDATIVE DAMAGE

Question 20

RNA Polymerase subunits

Answer 20

A1,a2,B,B’, Sigma

Question 21

Function of Sigma subunit RNA Polymerase

Answer 21

Associates with core enzyme to place it at the beginning of the gene to be transcribed. It recognizes the promoter.

Question 22

How transcription is terminated (2 methods)

Answer 22

Rho protein reads RNA being transcribed and dissociates complex when a certain sequence is seen.

OR

Base pairs at the end of the chain form a steam and loop , followed by a 4-U sequence ending transcription.

Question 23

RNA Pol I

Answer 23

Makes rRNA

Question 24

RNA Pol II

Answer 24

Makes mRNA

Question 25

RNA Pol III

Answer 25

Makes tRNA and 5S rRNA

Question 26

Proximal promoters

Answer 26

Islands of GCGC that bind regulatory proteins for house keeping genes.