Block 4 Biochem part 1 Flashcards Preview

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Flashcards in Block 4 Biochem part 1 Deck (185)
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1

who discovered that DNA is the source of heritable info?

oswald avery

2

who noticed the relationship btw AT and GC?

erwin chargaff

3

most common conformation of DNA

B DNA

4

dehydrated form of DNA

A DNA

5

form of DNA thought to help relieve stress of the helix around a transcription complex

Z DNA

6

Which enzyme binds the origin of replication in prokaryotes?

DnaA

7

how do bacteria regulate DNA replication?

they only make enough DNAA for 1 replication

8

what unwinds the DNA in prokaryotes?

helicase

9

what breaks the phosphodiester backbones to relieve supercoiling in prokaryotes?

Topoisomerase I

10

what makes clean breaks through both strands of DNA to unknot it?

Topoisomerase II

11

Main enzyme that copies DNA in prokaryotes

DNA pol III`

12

which enzyme in prokaryotes has 3'-->5' exonuclease activity for proofreading?

DNA pol III

13

what does DNA pol I do?

in prokaryotes, it excises the RNA primer and adds DNA

14

what is the eukaryotic equivalent of DNA pol I?

Fen-1 nuclease and RNase H

15

what does DNA ligase do?

in prokaryotes it ensures all phosphodiester bonds are formed

16

Polymerase alpha-

contains primase and initiates DNA synthesis

17

Polymerase delta-

synthesizes lagging strand (okizaki fragments) Has 3'-->5' exonuclease activity

18

polymerase epsilon-

synthesizes leading strand, has 3'-->5' exonuclease activity

19

polymerase beta-

repairs DNA. cannot excise ribonucleotides or proofread

20

polymerase gamma-

replicates mitochondrial DNA

21

the hexameric sequence of telomeres is:

AGGGTT

22

which end of a DNA strand does telomerase elongate?

the 3' end

23

After telomerase elongates a 3' end, ____ puts on a new primer at the end of the 3' telomere, _____ extends fills in the nucleotides, and _____ removes the RNA primer

-primase
-DNA pol delta
-FEN1 exonuclease

24

what nucleosides are often used to inhibit DNA synthesis?

AZT and 2',3' dideoxyinosine

25

most common base excision repair-

correcting deaminated cytosines

26

mismatch-directed DNA repair is mediated by ______

Mut proteins

27

Mut proteins work under the assumption that:

the template strand contains the correct base

28

in E. coli, the template strand is identified by:

methylation of adenine residues

29

in eukaryotes, the template strand is identified by:

being the "un-nicked strand"

30

_____ nicks the strand at mismatched nucleotides and _____ removes the them

-endonuclease
-exonuclease