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test 2 quiz questions Flashcards

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1
Q

The product of the regulator gene of the lac operon is

A

the repressor

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2
Q

A prokaryotic operon is composed of a series of adjacent genes under the control of

A

the same operator and promoter

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3
Q

the enzyme B-galactosidase can convert the disaccharide lactose into

A

allolactose, glucose, and galactose

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4
Q

the lac repressor protein controls expression of the lac operon by binding to the

A

lac operator site to repress expression

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5
Q

in the presence of the repressor molecule and free tryptophan, the trp operon is

A

repressed

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6
Q

In the presence of the repressor molecule and the absence of free tryptophan, the trp operon is

A

derepressed

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7
Q

the trp operon is controlled by

A

the Trp repressor and attenuation

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8
Q

any regulatory protein that acts by preventing transcription termination is called a(n)

A

antiterminator

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9
Q

the lac repressor (encodes by LacI) binds to

A

lactose and DNA

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10
Q

the order of the structural genes controlling the trp operon is

A

trpE, trpD, trpC, trpB, trpA.

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11
Q

In the classic experiment by Griffith, evidence of the action of a hereditary biomolecule was identified by

A

transformation (phenotypic change) of the R strain by S strain biomolecules

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12
Q

Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design. The key difference was:

A

systematically eliminating the impact of classes of S strain biomolecules using enzymatic digestion before mixing with R strain live cells.

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13
Q

Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design. They found that the enzyme ______________ was effective at destroying the transforming capacity of S strain biomolecules.

A

DNase (DNA destruction)

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14
Q

Chargaff’s rules do NOT hold for which of the following genome types?

A

single-stranded DNA virus

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15
Q

Of the three key building blocks of DNA, which type(s) of building block is/are negatively charged and oriented on the outside of the double helical structure?

A

phosphate

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16
Q

Which statement BEST describes the arrangement of components in a DNA molecule?

A

Nucleotides are located toward the inside of the strands and the phosphates toward the outside.

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17
Q

Which statement below BEST describes the situation between nucleotides on opposite strands in a DNA molecule?

A

A-T bonding between opposite strands involves two hydrogen bonds, whereas G-C bonding between strands involves three hydrogen bonds.

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18
Q

The replisome contains a protein subunit responsible for unwinding the double helix to enable DNA replication. This subunit/enzyme is named

A

helicase

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19
Q

Why does DNA with a high G + C content require higher temperatures to melt?

A

G–C base pairs have three hydrogen bonds.

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20
Q

When comparing the three key models of DNA replication, the model that included the separation of the two strands of the original DNA (template) and using those strands as templates to synthesize two new DNA strands is called

A

semiconservative replication

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21
Q

Topoisomerase and helicase have distinct functions that include which of the following?

A

Helicase is responsible for unwinding the double helix (separating strands).

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22
Q

The complexity of lagging strand replication is necessary because

A

as polymerization occurs only in the 5’-to-3’ direction, the lagging strand must be synthesized in consecutive small fragments.

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23
Q

Initiation of replication occurs at an “origin of replication” site that typically includes an AT-rich region. Initiation benefits from these AT-rich regions because

A

adenine-thymine pairs are held together by two H-bonds, making them easier to separate during unwinding.

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24
Q

When replicating the end of a chromosome, the lagging strand cannot copy the last ~10 nucleotides at the end of the chromosome. As a result, chromosomes contain telomere sequences at their ends, which are defined as

A

noncoding, repetitive sequences that can be copied independent of the replisome.

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25
Q

Primase and telomerase enzymes are both considered types of

A

reverse transcriptases

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26
Q

Template strand DNA and encoded RNA are

A

complementary of one another with antiparallel orientation.

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27
Q

RNA synthesis is always 5′ to 3′ because

A

nucleotides can only be added to an available 3′-OH group on the transcript terminus.

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28
Q

The role of tRNA is to

A

act as transporters bringing amino acids to the site of protein synthesis.

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29
Q

In a chromosome, which of the following is TRUE?

A

RNAs of different genes can be transcribed off either DNA strand, but always 5′ to 3′.

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30
Q

The sigma factor protein’s role in transcription in E. coli includes which of the following?

A

helps the holoenzyme to bind to the promoter

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31
Q

Why does E. coli have several different sigma factors?

A

They allow RNA polymerase to recognize and bind to a different subset of promoters.

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32
Q

Telomerase activity relies on ________________ for appropriate priming.

A

a short, telomeric RNA sequence that is carried within its structure

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33
Q

A key characteristic of bacterial RNAs that is NOT observed with eukaryotic RNAs is that

A

transcription can occur in the same cellular region as translation.

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34
Q

The carboxy-terminal domain of RNA polymerase II plays a key role in

A

capping of the 5′ end of a new transcript.
recruiting capping enzymes to the RNA polymerase enzyme.
addition of a poly(A) tail at the 3′ end of a transcript.
splicing of introns out of RNA transcripts.

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35
Q

What is the function of the TATA-binding protein?

A

allows eukaryotic RNA polymerase II to bind to the promoter of genes

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36
Q

Which of the following is/are role(s) of the 5’ cap?

A

The cap acts as a binding site for the ribosome and protects the RNA from degradation.

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37
Q

Which of the following constitutes the primary structure of a protein?

A

the linear sequence of amino acids in a polypeptide chain

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38
Q

How many nucleotides would be expected for a gene coding for a protein with 300 amino acids?

A

900

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39
Q

We know that DNA and RNA (each with four nucleotide components) both use a three-nucleotide genetic code and 64 codons (43 = 64). Knowing that the minimum number of codons for the genetic code is 21 (20 amino acids, 1 stop codon), what codon size would be required if only three nucleotides were present in the genome?

A

3 nucleotides per codon

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40
Q

Which could be an anticodon for the amino acid isoleucine?

A

UAA, UAG, and UAU

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41
Q

Delete

A

5′-AUG-3′ (RNA sense); 3′-UAC-5′ (tRNA anticodon); methionine

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42
Q

The aminoacyl-tRNA synthetase enzymes are responsible for

A

adding amino acids to appropriate tRNAs (charging the tRNA).

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43
Q

The anticodon on the tRNA molecule

A

binds to the mRNA in a complementary fashion.

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44
Q

The ribosome is the primary site of

A

protein synthesis

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45
Q

The A site, P site, and E site each control ______________ (in order) during translation.

A

binding incoming tRNAs (A), retention of the peptide chain during elongation (P), exit of deacylated tRNAs (E)

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46
Q

In bacteria, the Shine–Dalgarno sequence is found on the mRNA and is recognized by the ________________________ to reveal __________________________.

A

the 30S subunit; the translation start codon

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47
Q

which of the following is not one of the differences between DNA replication in bacteria and eukaryotes

A

bidirectional replication

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48
Q

what does telomerase add to the end of eukaryotic chromosomes

A

repetitive DNA sequences

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49
Q

RNA polymerase synthesizes which way

A

5’ to 3’

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50
Q

what DNA sequence attracts the binding of RNA polymerase

A

promoter consensus sequence

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51
Q

what allows the bacterial RNA polymerase to recognize different promoter with different consensus sequences

A

sigma factors

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52
Q

how many RNA polymerases does bacteria have?

A

1

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53
Q

how many RNA polymerases do eukaryotes have?

A

3

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54
Q

which RNA polymerase transcribes the insulin receptor gene

A

RNA pol 2

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55
Q

what happens at the same time in prokaryotes

A

transcription and translation

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56
Q

what happens at the same time in eukaryotes

A

transcription and transcript processing

57
Q

when mutation occurs to each of the three sites in a codon, which site is least likely to result in amino acid change?

A

3rd codon site

58
Q

start codon ?

A

AUG

59
Q

how many stop codons?

A

3

60
Q

how many subunits do ribosomes have?

A

one large subunit, one small subunit

61
Q

what is the function of the A site on ribosome

A

accepting the tRNA carrying amino acid

62
Q

what is the function of the p site on ribosome

A

the location where newly formed polypeptide is at

63
Q

what is the function of the e site on ribosome

A

exit site for tRNA

64
Q

mutation happens to the third site of the codon AGC (Ser) and changes codon AGA (Arg). we call this a

A

nonsynonymous mutation

65
Q

the negative control of gene expression is achieved through

A

repressor

66
Q

where does an effector bind on a repressor protein?

A

allosteric site

67
Q

how do activator or repressor proteins function as genetic switches

A

activator or repressor protein bind to operator sequences in the vicinity of the promoter to regulate transcription

68
Q

where is the binding location of repressor

A

operator

69
Q

where is the binding location of activator?

A

activator binding site

70
Q

what occurs as a result of allolactose binding to a repressor protein?

A

the repressor falls off the DNA, allowing RNA polymerase to begin transcription

71
Q

which of the following is an inducer of the lac operon

A

allolactose

72
Q

could the attenuation mechanism found in the trp operon regulate expression in eukaryotic cells

A

no, because transcription and translation only happen simultaneously in bacteria .

73
Q

helicase

A

is the enzyme that unzips the DNA by breaking through the hydrogen bonds between the DNA bases.

74
Q

Primase

A

Shows DNA polymerase where to start sequencing. it is made of RNA.

75
Q

DNA polymerase

A

replicates the DNA molecules to actually build a new strand of DNA

76
Q

Ligase

A

glues the DNA fragments together

77
Q

SSB proteins

A

bind to DNA strands to keep DNA strand separated

78
Q

topoisomerase

A

keeps DNA from supercoiling

79
Q

point of orgin DNA replication in bacteria

A

one

80
Q

point of orgin DNA replication in eukaryotes

A

many

81
Q

direction of DNA replication in eukaryotes and bacteria

A

bidirectional

82
Q

DNA polymerase 1 does what?

A

removes the RNA primers

83
Q

central dogma

A

DNA to mRNA to proteins

84
Q

mRNA

A

intermdeiate molecules used for transfer of information form DNA to protein

85
Q

rRNA

A

functional RNA molecules that are components of the ribosome

86
Q

tRNA

A

functional RNA molecules that serve as adapters in translation

87
Q

snRNA

A

functional RNA molecules that are involved in the removal of introns from pre-mRNA

88
Q

snoRNA

A

required fro tRNA processing

89
Q

RNA polymerase

A

opens the DNA double helix strand as template for transcription and then elongates the RNA strand using base complimentary as a guide.

90
Q

sigma factors

A

allow the bacterial RNA polymerase to recognize different promoter with different consensus sequences.

91
Q

transcription in eukaryotes only uses

A

RNA polymerase 2 even though there are 3

92
Q

TATA box

A

the most common eukaryotic promoter consensus sequence

93
Q

5’ capping

A

is a methylated guanine nucleotide added to 5’ that helps prevent degradation of mRNA, transports across the nuclear envelope, facilitate intron splicing, orient the mRNA for translation.

94
Q

3’ poly A tail

A

is a polyadenylation with 50-250 A nucleotides added to the 3’ end of cleaved mRNA that prevents degradation of the mRNA, transport across the nuclear envelope, and orient the mRNA for translation.

95
Q

introns

A

not useful DNA sequences so are spliced out in pre-mRNA

95
Q

the genetic code

A
  • codons do not overlap
  • codons have 3 nucleotides
  • is continuous without gaps
96
Q

self splicing introns

A

happens when two transesterification reactions occur, but the mRNA itself catalyzes the reactions without the need for a spliceosome.

96
Q

alternative splicing

A

allows multiple mRNA molecules to be produced from a single gene.

96
Q

which letter of codon does not normally change the code

A

the third letter

97
Q

ribosome

A

they bind mRNA & identify the start codon where translation begins. faciliated complementary base pairing of mRNA codons & the correspondng tRNA anticodons. catalyze formation of peptide bond between the amino acids.

98
Q

ribosme composition

A

made of one large subunit and one small subunit.

99
Q

third base wobble

A

g can be paired with c or u
u can be paired with a or g

100
Q

synontmous codons

A

code for the same anmino acid

101
Q

how to extract DNA

A

homogenize the tissue using detergent, then remove protein using proteases and salts, then precipitate DNA using alcohol.

102
Q

how is DNA and RNA charged?

A

negatively

103
Q

how do we separate mRNA from RNA

A

through oligo (dt) purification: mix particles with sample, hybridization of polyA tail with magnetic particles, apply magnetic field for mRNA separation.

104
Q

How many molecules of histones H2A, H2B, H3, and H4 (respectively) comprise a single nucleosome?

A

two each (2,2,2,2)

105
Q

Which of the following describes the histones associated with the nucleosomes of active genes?

A

rich in acetyl groups

106
Q

Which of the following describes the histones associated with the nucleosomes of inactive genes?

A

poor in acetyl groups

107
Q

The enzyme responsible for adding acetyl groups to histone proteins is called

A

histone acetyltransferase (HAT)

108
Q

The enzyme responsible for removing acetyl groups from histone proteins is called

A

histone deacetylase (HDAC)

109
Q

The enzyme responsible for adding methyl groups to histone proteins is called

A

histone methyltransferase (HMT)

110
Q

Epigenetic inheritance is defined as the inheritance of

A

chromatin states form one cell generation to the next

111
Q

What portion of a histone is typically modified by acetylation/deacetylation?

A

basic amino acid residues in the “tail” region of the histone

112
Q

what is chromatin remodeling

A

the changing of nucleosome position

113
Q

compared to heterochromatin, euchromatin is

A

rich in genes and comprised of loosely packed nucleosomes.

114
Q

which type RNA is translated into protreins

A

mRNA

115
Q

the process by which pneumococcus transfers DNA between living type RII and heat killed type SII cells is known as

A

transformation

116
Q

what is the bond between the phosphate and nucleotide

A

phosphodiester bond

117
Q

what is required for DNA polymerase to initiate DNA strand synthesis

A

a short RNA primer synthesized by the enzyme primase

118
Q

what is the temperature cycle for pcr

A

95 - 55 - 72

119
Q

pyrimidines

A

thymine and cytosine

120
Q

purines

A

adenine and guanine

121
Q

what would you expect to see if DNA helicase activity is inhibited

A

helicase catalyzes ATP hydrolysis and DNA strands separation, so the helix cannot be unwound and strands will not separate

122
Q

if SSB proteins were not present what is to be expected

A

the strands would quickly reannel and DNA replication cannot proceed

123
Q

the extraordinary accuracy of the DNA polymerase III enzyme lies in its ability to “proofread” newly synthesized DNA, a functiion of the enzyme’s ….

A

3’ to 5’ exonuclease activity

124
Q

what is the minimum number of such crossover events needed for integration?

A

2

125
Q

which of the following would you find in a Sanger sequencing but not in a polymerase chain reaction?

A

ddNTPs

126
Q

the shine-dalgarno sequence in bacteria

A

is a purine-rich consensus sequence found in the 5’ UTR of the mRNA

127
Q

during translation initiation in prokaryotes, the amino acid on the initiator tRNA is

A

N-formylmethionine (fMet)

128
Q

how does the eukaryotic initiation complex locate the true start codon?

A

the true start codon is the first ATG encountered downstream of the Kozak sequence

129
Q

what would you expect to find bound to the stop codon at the A site?

A

a release factor

130
Q

in the unlikely event that a tRNA has been charged with the wrong amino acid, what high-fidelity enzyme is likely to blame?

A

aminoacyl synthetase

131
Q

in the lac operon what acts as the inducer

A

allolactose

132
Q

in negativce control, what molecule would you expect to find bound to the operator if there is no transcription

A

repressor

133
Q

the enzyme B-galactoside catalyzes what?

A

lactose to galactose and glucose

134
Q

a bacterium is unable to transport lactpse into the cell to be broken down. which gene is likely mutated in this bacterium?

A

lacY

135
Q
A

genetics (4 decks)

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