Genetics Chpt. 12 and 13

Question 1

How many bands of DNA would be expected in
Meselson and Stahl’s experiment after two rounds
of conservative replication?

Answer 1

two

Question 2

Replicons

Answer 2

units of replication

Question 3

Conservative Replication

Answer 3

one is entirely new DNA, and the other is made of old DNA strands

Question 4

Dispersive Replication

Answer 4

the original DNA double helix breaks apart into fragments, and each fragment then serves as a template for a new DNA fragment

Question 5

Semi-Conservative Replication

Answer 5

every new DNA double helix would be a hybrid that consisted of one strand of old DNA bound to one strand of newly synthesized DNA

Question 6

Theta

Answer 6

circular DNA, no break in nucleotide strand, 1 replicon, unidirectional/bidirectional

Question 7

Rolling-Circle

Answer 7

circular DNA, break in nucleotide strand, 1 replicon, unidirectional

Question 8

Linear Eukaryotic

Answer 8

linear DNA, no break in nucleotide strand, many replicons, bidirectional

Question 9

Which type of replication requires a break in the
nucleotide strand to get started?

Answer 9

Rolling-Circle Replication

Question 10

Requirements for DNA Replication

Answer 10

template strand, nucleotides, enzymes and other proteins

Question 11

DNA replication takes place in a

Answer 11

semiconservative model

Question 12

Replication runs from

Answer 12

5’ to 3’

Question 13

Nucleotides get added to what end

Answer 13

3’

Question 14

Leading Strand

Answer 14

undergoes continuous replication

Question 15

Lagging Strand

Answer 15

undergoes discontinuous replication

Question 16

Okazaki Fragments

Answer 16

discontinuously synthesized
short DNA fragments forming the lagging strand

Question 17

Discontinuous replication is a result of which
property of DNA?

Answer 17

antiparallel nucleotide strands

Question 18

Place the following components in the order in
which they are first used in the course of
replication:
helicase
single-strand-binding protein
DNA gyrase
initiator protein

Answer 18

initiator protein, helicase, single-strand-binding protein, DNA gyrase

Question 19

Primers

Answer 19

an existing group of RNA nucleotides with a
3’-OH group to which a new nucleotide can be
added; they are usually 10–12 nucleotides long

Question 20

Primase

Answer 20

RNA polymerase…synthesize primers with a 3’-OH group at the beginning of each DNA fragment

Question 21

Primers are synthesized where on the lagging
strand?

Answer 21

at the beginning of every okazaki fragment

Question 22

Helicase

Answer 22

unwinds the DNA

Question 23

Single-Strand-Binding Proteins

Answer 23

protect the single nucleotide strands and prevent secondary structures

Question 24

DNA Gyrase

Answer 24

remove strain ahead of the replication fork

Question 25

DNA Polymerase I

Answer 25

removes and replaces primers

Question 26

DNA Polymerase III

Answer 26

carries out elongation

Question 27

Ligase

Answer 27

connects nicks (Okazaki fragments) after RNA primers are removed

Question 28

Termination

Answer 28

when the replication fork meets or by a termination protein

Question 29

DNA Polymerase II

Answer 29

DNA repair; restarts replication DNA; halts synthesis

Question 30

DNA Polymerase IV

Answer 30

DNA repair

Question 31

DNA Polymerase V

Answer 31

DNA repair; translesion DNA synthesis

Question 32

Polymerase generally

Answer 32

synthesized the leading and lagging strands

Question 33

Which bacterial enzyme removes the primers?

Answer 33

DNA polymerase I

Question 34

Proofreading

Answer 34

DNA polymerase I: 3' - 5' exonuclease activity removes the incorrectly paired nucleotide

Question 35

Mismatch Repair

Answer 35

corrects errors after replication is complete

Question 36

Which mechanism requires the ability to distinguish between newly synthesized and template strands of DNA?

Answer 36

mismatch repair

Question 37

In comparison with prokaryotes, what are some differences in the genome structure of eukaryotic cells that affect how replication takes place?

Answer 37

The size of eukaryotic genomes, the linear structure of eukaryotic chromosomes, and the association of DNA with histone proteins

Question 38

Some of the eukaryotic DNA polymerases have a tendency to make errors in replication. Why would a cell use an error-prone DNA polymerase instead of one that is more accurate?

Answer 38

Error-prone DNA polymerases can bypass lesions in the DNA helix that stall accurate, high-speed DNA polymerases

Question 39

What would be the result if an organism’s telomerase were mutated and nonfunctional?

Answer 39

Chromosomes would shorten each generation

Question 40

Why is recombination important?

Answer 40

Recombination is important for genetic variation and for some types of DNA repair.

Question 41

What is the function of resolvase in recombination?

Answer 41

It cleaves the Holliday structure

Question 42

Ribozymes

Answer 42

catalytic RNA

Question 43

Ribosomal RNA (rRNA)

Answer 43

structural and functional components of the ribosome

Question 44

Messenger RNA (mRNA)

Answer 44

carries genetic code for proteins

Question 45

Transfer RNA (tRNA)

Answer 45

helps incorporate amino acids into polypeptide chain

Question 46

Transcription requires

Answer 46

DNA template, raw materials (ribonucleotide triphosphates), transcription apparatus

Question 47

Transcribed strand is

Answer 47

template strand

Question 48

The transcription unit is composed of

Answer 48

a promoter, RNA-coding sequence, and terminator

Question 49

What is the difference between the template strand and the nontemplate strand?

Answer 49

The template strand is the DNA strand that is copied into an RNA molecule, whereas the nontemplate strand is not copied

Question 50

Which of the following phrases does NOT describe a function of the promoter?

Answer 50

signals where transcription ends

Question 51

Sigma Factor

Answer 51

binding to the promoter when transcription starts

Question 52

In transcription, nucleotides are added to the

Answer 52

3' end

Question 53

What is the function of the sigma factor?

Answer 53

The sigma factor controls the binding of RNA polymerase to the promoter

Question 54

What binds to the −10 consensus sequence found in most bacterial promoters?

Answer 54

holoenzyme (core enzyme + sigma factor)

Question 55

What characteristics are most commonly found in rho-independent terminators?

Answer 55

inverted repeats followed by a string of adenine nucleotides

Question 56

The promoters of genes transcribed by RNA polymerase II consists of two primary parts

Answer 56

a core promoter and a regulatory promoter

Question 57

What is the difference between the core promoter and the regulatory promoter?

Answer 57

Both b and c above

Question 58

What is the role of TFIID in transcription initiation?

Answer 58

RNA polymerase over the transcription start site

Question 59

How are the processes of RNA polymerase II termination in eukaryotes and rho-dependent termination in bacteria similar, and how are they different?

Answer 59

Both processes use a protein that binds to the RNA molecule and moves down the RNA toward the RNA polymerase. They differ in that rho does not degrade the RNA, whereas Rat1 does.