Chapter 6 - Molecular Genetics

Question 1

nucleotide

Answer 1

ribose sugar attached to both a nitrogenous base and a phosphate group

Question 2

nucluoside

Answer 2

ribose sugar only attached to a nitrogenous base but no phosphate group

Question 3

DNA and RNA are polymers of:

Answer 3

nucleotides

Question 4

DNA has __ at 2’ carbon

Answer 4

H

Question 5

RNA has __ at 2’ carbon

Answer 5

OH

Question 6

purines

Answer 6

adenine and guanine

Question 7

pyrimidines

Answer 7

cytosine, thymine, uracil

Question 8

Which nucleosides have double rings?

Answer 8

purines

Question 9

Which nucleosides have a single ring?

Answer 9

pyrimidines

Question 10

C and G form:

Answer 10

3 H bonds

Question 11

A and T/U form:

Answer 11

2 H bonds

Question 12

DNA wraps around proteins called

Answer 12

histones

Question 13

Histones are ____ charged

Answer 13

positively

Question 14

Nucleosome

Answer 14

DNA histone complex

Question 15

Central core of histones

Answer 15

H2A, H2B, H3, H4 (2 of each)

Question 16

__ keeps DNA wrapped around the central histone core

Answer 16

H1

Question 17

When the cell is not dividing, DNA is packaged into _____ or _____

Answer 17

euchromatin or heterochromatin

Question 18

Loosely packed DNA

Answer 18

euchromatin

Question 19

Tightly packed DNA

Answer 19

heterochromatin

Question 20

How does the cell change how tightly DNA is bound?

Answer 20

acetylation or deacetylation

Question 21

Acetylation of histones causes DNA to become:

Answer 21

more loosely packed. relieves positive charge of histone so not as much electrostatic attraction

Question 22

Deacetylation of histones causes DNA to become:

Answer 22

more tightly packed

Question 23

Histone methylation causes:

Answer 23

upregulation or downregulation of transcription

Question 24

Can DNA be methylated?

Answer 24

Yes, but usually used to suppress transcription by recruiting methyl-binding proteins and preventing transcription factors from binding to the DNA

Question 25

First step of DNA replication

Answer 25

initiation - formation of origin of replication

Question 26

___ has one origin of replication

Answer 26

Bacteria

Question 27

___/___ have multiple origins of replication

Answer 27

Eukarya and Archaea

Question 28

DNA replication is a ____ process

Answer 28

semiconservative

Question 29

Origins of replication tend to occur at:

Answer 29

AT rich segments

Question 30

Which enzyme unzips DNA double helix

Answer 30

Helicase

Question 31

Unzipping of DNA causes

Answer 31

supercoiling (tension at replication fork)

Question 32

Which enzyme relieves supercoiling of DNA

Answer 32

topoisomerase

Question 33

DNA gyrase

Answer 33

subtype of DNA topoisomerase found in bacteria and plants

Question 34

DNA polymerase III

Answer 34

adds new nucleotides to 3’ end of existing strand

Question 35

primase

Answer 35

places RNA primer at origin of replication which allows DNA Pol III to extend DNA strand

Question 36

___ holds DNA polymerase to the template strand

Answer 36

Sliding clamp proteins

Question 37

DNA Pol reads ____ strand in what direction?

Answer 37

template; 3’ to 5’

Question 38

Leading strand

Answer 38

synthesized continuously, only requires one RNA primer

Question 39

Lagging strand

Answer 39

synthesized discontinuously; requires one RNA primer for each Okazaki fragment

Question 40

What enzyme replaces RNA primers with DNA segments?

Answer 40

DNA Pol I

Question 41

Ligase

Answer 41

forms phosphodiester bonds between separated strands

Question 42

True or false: DNA Pol cannot proofread as it elongates DNA

Answer 42

false ; several DNA Pols have proofreading ability that allows them to double check their work

Question 43

How does termination of DNA replication occur

Answer 43

When 2 replication forks meet