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Flashcards in Exam and Pretest Questions Deck (114):
1

Which statement about DNA polymerase III is FALSE?

a. It is responsible for incorporating most of the nucleotides in the leading strand.

b. It contains a 3' to 5' proofreading activity.

c. It is responsible for incorporating most of the nucleotides in the lagging strand.

d. It does not require primers to extend the leading strand.

e. It has a very low error rate.

d. It does not require primers to extend the leading strand.

2

One function of DNA pol I during replication in prokaryotes is to:

a. join the ends of adjacent Okazaki fragments together

b. separate the double-stranded DNA into single-stranded regions

c. replicate the lagging strand of DNA in eukaryotic cells

d. relieve tension induced by supercoiling

e. remove the RNA primers that initiate replication

a. join the ends of adjacent Okazaki fragments together

3

The enzyme used in making cDNA is:

a. DNA ligase

b. a thermostable DNA polymerase

c. reverse transcriptase

d. polynucleotide kinase

e. the single-stranded binding protein PCNA

c. reverse transcriptase

4

7-methyl-guanosine is added to mRNA molecules during a processing reaction in eukaryotes. The unique processing event is a:

a. 3'-5' triphosphate linkage at the 3’ end of the RNA

b. 2'-5' triphosphate linkage at the 5’ end of the RNA

c. 3'-5' triphosphate linkage at the 5’ end of the RNA

d. 3'-2' triphosphate linkage at the 3’ end of the RNA

e. 5'-5' triphosphate linkage at the 5’ end of the RNA

e. 5'-5' triphosphate linkage at the 5’ end of the RNA

5

The reduced expression of the lac operon in the presence of glucose is an example of :

a. transcriptional activation

b. catabolite repression

c. operon silencing

d. regulatory dominance

e. anabolic repression

b. catabolite repression

6

Attenuation at the trp operon in E. coli occurs when:

a. translation and transcription become uncoupled

b. high tryptophan levels inhibit the binding of a repressor protein

c. low tryptophan levels increase the rate of RNA polymerase progression

d. high tryptophan levels allow the formation of a terminator stem-loop in the trpL mRNA

e. the tryptophan membrane transporter increases the rate of tryptophan import

d. high tryptophan levels allow the formation of a terminator stem-loop in the trpL mRNA

7

Which is most commonly found in the P site of ribosomes?

a. a tRNA with the growing peptide chain attached

b. a tRNA with no amino acid attached

c. a tRNA with a single amino acid attached

d. ribosome releasing factor

e. termination factor

a. a tRNA with the growing peptide chain attached

8

Which statement about the Shine-Delgarno sequence is FALSE?

a. it is found near the 5’ end of prokaryotic mRNAs.

b. it is complementary to a sequence near the 3’ end of the 16S rRNA.

c. it helps position the small ribosomal subunit near the translation start site.

d. it contains the AUG initiator codon.

e. it is required for efficient translation.

d. it contains the AUG initiator codon.

9

Which of the following methods would be used to determine the amino acid sequence of a peptide?

a. polymerase chain reaction

b. western blotting

c. organism cloning

d. gel shift assay

e. mass spectrometry

e. mass spectrometry

10

Mass spectrometry can detect all of these EXCEPT:

a. proteins that have been post-translationally modified.

b. proteins made from mRNAs that have been alternatively spliced.

c. proteins made from mRNAs that have used alternate polyadenylation sites.

d. proteins present in cancer cells but not in normal cells.

e. proteins that have been localized in the wrong cellular compartment.

e. proteins that have been localized in the wrong cellular compartment.

11

Which of the following types of mutation is likely to have the greatest consequence to the cell?

a. a G => A change that creates a stop codon within a gene

b. trisomy of an autosome

c. an insertion of a T in a homopolymeric run of Ts

d. an inversion of the long arm of the X chromosome

e. a reciprocal translocation between two autosomes

b. trisomy of an autosome

12

A scientist suspects that a short translocation has occurred that might involve a gene that she is studying. What is the fastest way to determine if the cells carry the translocation?

a. sequence the genome with DNA from the cells

b. use PCR to amplify the gene

c. use a labeled probe of the gene to do in situ hybridization

d. do a chromosome walk with the gene as an initial probe

e. construct a YAC library from the cell’s DNA

c. use a labeled probe of the gene to do in situ hybridization

13

Which statement about RNA interference is FALSE?

a. it occurs only in plants.

b. it involves short RNAs that are complementary to the target mRNA.

c. it can inhibit the transcription of the target mRNA.

d. it can cause the degradation of the target mRNA.

e. it can inhibit the translation of the target mRNA.

a. it occurs only in plants.

14

The function of helicases during replication is to join the ends of adjacent Okazaki fragments together

True or False?

False

15

The function of helicases during replication is to separate the DNA strands from each other.

True or False?

True!

16

The function of helicases during replication is to relieve tension induced by supercoiling.

True or False?

False

17

The function of helicases during replication is to remove the RNA primers that initiate replication.

True or False?

False

18

Microarrays are useful when studying the gene expression in cancer cells because they can identify all of the genes that are overexpressed.

True or False?

True

19

Microarrays are useful when studying the gene expression in cancer cells because they can identify all of the genes that are underexpressed.

True or False?

True

20

Microarrays are useful when studying the gene expression in cancer cells because they can identify all of the genes that have point mutations.

True or False?

False

21

The following DNA mutation is likely to result in a shorter than normal mRNA:

True / False

1. A -> C at position 10

2. G -> A at position 13

3. C -> A at position 18

Q image thumb

1. False

2. False

3. False

22

The following DNA mutation is likely to result in a shorter than normal protein:

True / False

1. T -> C at position 19

2. A -> G at position 21

3. insertion of a G after the G at position 14

Q image thumb

1. False

2. False

3. True

23

In partially diploid E. coli cells with the genotype F' i+ o- z- y+ a-/ chromosome i- o+ z+ y- a+, which functional gene product(s) would be expressed at high level in the absence of lactose?

True / False

1. β-galactosidase only

 2. β-galactosidase, permease, and transacetylase

3. permease only

 4. permease and transacetylase

1. False

2. False

3. True

4. False

24

Which of the following statements about nucleotides are true and which are false?

True / False

1. The phosphate group is attached to the nitrogenous base. 

2. A nucleotide contains a base, a sugar, and a phosphate group. 

3. The sugar contains two nitrogen atoms. 

4. The nitrogenous base is attached to the sugar by a glycosidic bond.

1. False

2. True

3. False

4. True

25

Histone acetyltransferases act to:

True / False

1. eliminate the positive charge of lysines in histones 

2. increase the compaction of DNA around histones 

3. help the histones reassemble following DNA replication 

4. prevent the translation of histone mRNA molecules 

5. remove covalent modifications on the lysine residues of histones

1. True

2. False

3. False

4. False

5. False

26

During protein synthesis, the tRNA synthetase acts to:

True / False

1. attach an amino acid to the anticodon of the tRNA  

2. transcribe the genes encoding tRNAs to produce tRNA molecules

3. serve as the first initiation factor during ribosome assembly 

4. covalently bind an amino acid to the acceptor stem of the tRNA 

5. cause precursor tRNA molecules to adopt their proper final structure

1. False

2. False

3. False

4. True

5. False

27

The following are tRNA binding sites found within ribosomes:

True / False

1. peptidyl site  

2. exit site 

3. elongation site 

4. aminoacyl site

1. True

2. True

3. False

4. True

28

For which of the following experiments would a DNA microarray be useful?

True / False

1. identifying the binding site for a transcription factor 

2. determining which genes are induced when a chemical is added to a cell’s growth medium  

3. determining which genes are down-regulated in response to heat shock  

4. identifying the site of a DNA inversion  

5. distinguishing between two closely related bacterial subspecies

1. True

2. True

3. True

4. False

5. True

29

In each blank, put the letter of the process that is most associated with the given phrase or word.

URE​

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

 

d. transcription

30

In each blank, put the letter of the process that is most associated with the given phrase or word.

Shine-Delgarno sequence

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

e. translation

31

In each blank, put the letter of the process that is most associated with the given phrase or word.

tRNA

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

e. translation

32

In each blank, put the letter of the process that is most associated with the given phrase or word.

non-template strand

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

d. transcription

33

In each blank, put the letter of the process that is most associated with the given phrase or word.

AUG codon

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

e. translation

34

In each blank, put the letter of the process that is most associated with the given phrase or word.

primase

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

b. DNA replication

35

In each blank, put the letter of the process that is most associated with the given phrase or word.

TATA box

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

d. transcription

36

In each blank, put the letter of the process that is most associated with the given phrase or word.

splicing

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

c. RNA processing

37

In each blank, put the letter of the process that is most associated with the given phrase or word.

Pribnow box

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

d. transcription

38

In each blank, put the letter of the process that is most associated with the given phrase or word.

hemi-methylated DNA

 a. DNA repair

b. DNA replication

c. RNA processing

d. transcription

e. translation

 a. DNA repair

39

In a gene, the DNA strand that has the same sequence of nucleotides as the mRNA transcribed from that gene is known as the                                 strand.

non-template or sense or coding

40

The coding sequences in eukaryotic genes that are joined during pre m-RNA splicing are called             .

exons.

41

Thymine crosslinked dimers in DNA are usually fixed by which repair mechanism?

Nucleotide excision repair

42

A Northern blot is used to detect what type of molecule?

RNA

43

What type of probe(s) is used in a Northern blot?

Nucleic acid: DNA, RNA, oligo, etc.

44

A Southern blot is used to detect what type of molecule?

DNA

45

What type of probe(s) is used in a Southern blot?

Nucleic acid: DNA, RNA, oligo, etc.

46

A Western blot is used to detect what type of molecule?

protein

47

What type of probe(s) is used in a Western blot?

antibody

48

In dideoxy DNA sequencing, which carbons on the sugar portion of the nucleotide lack OH groups?

2’ and 3

49

Which base is not found in DNA?

a. adenine

b. cytosine

c. guanine

d. uracil

e. thymine

d. uracil

50

Which statements best describe a nucleotide? (More than one may be correct)

a. the phosphate group is attached to the base

b. a nucleotide contains a base, a sugar, and a phosphate group

c. the sugar contains two nitrogen atoms

d. the bases contain extra-cyclic groups such as NH2 or O

e. the base is attached to the sugar by a glycosidic bond

b. a nucleotide contains a base, a sugar, and a phosphate group

d. the bases contain extra-cyclic groups such as NH2 or O

e. the base is attached to the sugar by a glycosidic bond

51

 Which are features of a DNA double helix? (More than one may be correct)

a. the bases interact by covalent bonding

b. the sugar-phosphate backbone is on the outside of the helix

c. each base pair contains either two purines or two pyrimidines

d. the backbones of the two strands run in opposite directions

e. bases are positioned perpendicular to the overall axis of the DNA strand

b. the sugar-phosphate backbone is on the outside of the helix

d. the backbones of the two strands run in opposite directions

e. bases are positioned perpendicular to the overall axis of the DNA strand

52

Which statements about RNA are false?

a. RNA differs from DNA by containing ribose, not deoxyribose sugars

b. RNA contains uracil instead of thymine

c. RNA secondary structure is more variable than DNA

d. none of these statements are false

d. none of these statements are false

53

Separating the double helix into single strands during replication requires which protein?

a. DNA polymerase I

b. DNA polymerase II

c. helicase

d. topoisomerase

e. primase

c. helicase

54

Leading and lagging strand synthesis differs in that:

a. On the leading strand, synthesis is 5’ to 3’ but 3’ to 5’ on the lagging

b. Leading strand synthesis does not require topoisomerase, unlike lagging strand synthesis

c. The leading strand requires only a single primer, while the lagging strand requires multiple primers

d. Helicases open the leading strand faster than the lagging strand

c. The leading strand requires only a single primer, while the lagging strand requires multiple primers

55

The technique used to determine that DNA replication occurs semi-conservatively was:

a. X-ray crystallography

b. electron microscopy

c. sequencing

d. equilibrium density-gradient centrifugation

e. microarray analysis

d. equilibrium density-gradient centrifugation

56

All of the following are properties of DNA polymerase III except:

a. It completes synthesis of the leading strand before beginning synthesis of the lagging strand

b. It is responsible for incorporating most of the nucleotides in the lagging strand

c. It is responsible for incorporating most of the nucleotides in the leading strand

d. It contains a 3’ to 5’ proofreading activity

e. It has a very low error rate

a. It completes synthesis of the leading strand before beginning synthesis of the lagging strand

57

If the sequence ACATA mutates to become ACTTA, the A to T alteration is called a:

a. depurination

b. transversion

c. transition

d. tautomeric shift

b. transversion

58

Which of these DNA repair mechanisms does not use DNA polymerase during repair?

a. homologous recombinational repair of a double-strand break

b. base excision repair of an apurinic site

c. mitotic mismatch repair

d. photolyase repair of a thymine dimer

e. nucleotide excision repair of a thymine dimer

d. photolyase repair of a thymine dimer

59

A tautomeric shift during replication most likely results in a:

a. missense mutation

b. deletion mutation

c. frameshift mutation

d. insertion mutation

e. inversion mutation

a. missense mutation

60

Site-directed mutagenesis:

a. can be used to restore a mutant gene back to wild-type sequence

b. can be used to modify the function of a gene

c. can be used to modify the binding site for a repressor in the 5’ untranslated region of a gene

d. all of the above

e. none of the above

d. all of the above

61

Which of the following are NOT characteristics of a DNA double helix?

a. nitrogenous bases on the inside of the helix

b. strands antiparallel

c. 25 bases per one turn of the helix

d. A-T base pairs contain two hydrogen bonds, C-G base pairs contain 3 hydrogen bonds

c. 25 bases per one turn of the helix

62

How do purines and pyrimidines differ?

a. pyrimidines have a double ring while purines have a single ring structure

b. purines are the components of RNA; pyrimidines are only found in DNA

c. purines have double ring while pyrimidines have a sing ring structure

d. pyrimidines are only found in RNA; purines are the components of DNA

c. purines have double ring while pyrimidines have a sing ring structure

63

Which of the following statements about the major groove of double stranded DNA is true?

a. It is narrower than the minor groove.

b. It refers to the space between the sugar and the phosphate on the DNA backbone.

c. It allows proteins to ‘read’ the DNA sequence without disrupting the double helix.

d. All of the statements are correct.

e. None of the statements are correct.

c. It allows proteins to ‘read’ the DNA sequence without disrupting the double helix.

64

One function of DNA pol I during replication in prokaryotes is to:

a. join the ends of adjacent Okazaki fragments together

b. separate the double-stranded DNA into single-stranded regions

c. replicate the lagging strand of DNA in eukaryotic cells

d. relieve tension induced by supercoiling

e. remove the RNA primers that initiate replication

e. remove the RNA primers that initiate replication

65

Which of the following is NOT a property of DNA polymerase III?

a. It is responsible for incorporating most of the nucleotides in the leading strand.

b. It contains a 3' to 5' proofreading activity.

c. It is responsible for incorporating most of the nucleotides in the lagging strand.

d. It does not require primers to extend the leading strand.

e. It has a very low error rate.

d. It does not require primers to extend the leading strand.

66

If the sequence GTGAT mutates to become GTAAT, the G to A alteration is called a:

a. depurination

b. transversion

c. transition

d. tautomeric shift

c. transition

67

Which of the following is NOT a step in the repair of a deaminated cytosine?

a. N-glycosylase to remove the damages base

b. primase to synthesize an RNA primer

c. apyrimidinic endonuclease to nick the backbone at the damaged base

d. DNA polymerase to add the correct base

e. DNA ligase to seal the nick in the backbone

b. primase to synthesize an RNA primer

68

Site-directed mutagenesis:

a. can be used to produce a specific allele of a gene

b. can be used to modify the function of a gene

c. can be used to modify the binding site for a repressor in the 5’ untranslated region of a gene

d. can be used to restore a mutant gene back to wild-type sequence

e. all of the above

e. all of the above

69

Restriction enzymes usually only cut foreign viral DNA and ignore their own bacterial DNA. The reason for this behavior is:

a. their bacterial DNA is methylated

b. transcriptional repression of the restriction enzyme’s structural gene

c. translational modification of the restriction enzyme

d. the heterochromatin state of the bacterial DNA

e. the foreign viral DNA is methylated

a. their bacterial DNA is methylated

70

The enzyme used in PCR is:

a. DNA ligase

b. a thermostable DNA polymerase

c. reverse transcriptase

d. the restriction endonuclease PvuII

e. the single-stranded binding protein PCNA

b. a thermostable DNA polymerase

71

A tautomeric shift during replication can cause the following type of mutation:

True / False

1. missense mutation 

2. repeat tract expansion 

3. silent mutation 

4. frameshift mutation 

5. neutral mutation

1. True

2. False

3. True

4. False

5. True

72

Which of the following statements about RNA and DNA are true and which are false?

True / False

1. RNA contains ribose rather than deoxyribose sugars 

2. DNA secondary structure is less variable than RNA 

3. RNA polymers incorporate uracil  

4. RNA has a –OH group on the 2’ carbon that DNA lacks 

5. RNA cannot serve as the genetic information storage medium

1. True

2. True

3. True

4. True

5. False

73

The function of topoisomerases during replication is to:

True / False

1. join the ends of adjacent Okazaki fragments together 

2. separate the DNA strands from each other  

3. relieve tension induced by supercoiling  

4. remove the RNA primers that initiate replication 

5. generate the primer used to initiate synthesis

1. False

2. False

3. True

4. False

5. False

74

We discussed a number of different types of DNA repair mechanisms: recombinational repair, mismatch repair, base excision repair, nucleotide excision repair, and DNA proofreading. Each of the repair mechanisms acts on a specific substrate. Which repair mechanism acts on each of the following types of damage?

... an apurinic site?

Base excision repair

75

We discussed a number of different types of DNA repair mechanisms: recombinational repair, mismatch repair, base excision repair, nucleotide excision repair, and DNA proofreading. Each of the repair mechanisms acts on a specific substrate. Which repair mechanism acts on each of the following types of damage?

...a thymine dimer?

nucleotide excision repair, or photolyase

76

We discussed a number of different types of DNA repair mechanisms: recombinational repair, mismatch repair, base excision repair, nucleotide excision repair, and DNA proofreading. Each of the repair mechanisms acts on a specific substrate. Which repair mechanism acts on each of the following types of damage?

...a T:C base pair in interphase?

mismatch repair or DNA proofreading

77

We discussed a number of different types of DNA repair mechanisms: recombinational repair, mismatch repair, base excision repair, nucleotide excision repair, and DNA proofreading. Each of the repair mechanisms acts on a specific substrate. Which repair mechanism acts on each of the following types of damage?

...a double-stranded break?

recombinational repair

78

We discussed a number of different types of DNA repair mechanisms: recombinational repair, mismatch repair, base excision repair, nucleotide excision repair, and DNA proofreading. Each of the repair mechanisms acts on a specific substrate. Which repair mechanism acts on each of the following types of damage?

...an A:G base pair during DNA synthesis?

DNA proofreading

79

Which RNA polymerase component is required for promoter recognition?

a. alpha (α)

b. beta (β)

c. beta prime (β’)

d. sigma (σ)

e. omega (ω)

Q image thumb

d. sigma (σ)

80

Attenuation of the trp operon occurs when:

a. the trp repressor binds to the operator

b. the corepressor molecules are released from the repressor

c. specific stem-loop structures form in the RNA

d. the cell lacks charged tryptophan tRNA molecules

e. All of these

c. specific stem-loop structures form in the RNA

81

E. coli DNA replication and transcription are similar in that:

a. both use DNA Polymerase III

b. both use dNTPs

c. both require formation of an open bubble to initiate synthesis

d. both require primers to initiate synthesis

e. both make copies of each strand during synthesis

c. both require formation of an open bubble to initiate synthesis

82

Which of the following is the small effector molecule that binds to CAP (catabolic activator protein)?

a. allolactose

b. glucose

c. tryptophan

d. cAMP

e. mediator

d. cAMP

83

Steroids act in transcription regulation by:

a. directly binding and activating RNA Polymerase II

b. binding to and inactivating repressor proteins

c. displacing inhibitor proteins from transcription factors

d. binding to a surface receptor that activates a transcription factor

e. none of the above

c. displacing inhibitor proteins from transcription factors

84

Histone acetyltransferases act by:

a. adding phosphate groups to serines of histone proteins

b. adding acetyl groups to serines of histone proteins

c. adding phosphate groups to lysines of histone proteins

d. adding acetyl groups to lysines of histone proteins

e. moving acetyl groups from histone proteins to transcription factors

d. adding acetyl groups to lysines of histone proteins

85

Which of the following is not a domain found within transcription factors?

a. zinc finger

b. basic domain

c. cytosine zipper

d. helix-turn-helix

e. glutamine-rich domain

c. cytosine zipper

86

A single nucleosome is composed of:

a. Eight histone proteins, linker proteins, and about 146 bp of DNA

b. Eight histone proteins and about 146 bp of DNA

c. Six histone proteins and about 146 bp of DNA

d. Four histone proteins and about 146 bp of DNA

b. Eight histone proteins and about 146 bp of DNA

87

Which of the following processing events are not used with prokaryotic tRNAs:

a. endonucleolytic cleavage

b. exonucleolytic cleavage

c. base modifications

d. poly-A tailing

d. poly-A tailing

88

7-methyl-guanosine is added to mRNA molecules during a processing reaction in eukaryotes. The unique processing event is a:

a. 3'-5' triphosphate linkage at the 3’ end of the RNA

b. 2'-5' triphophate linkage at the 5’ end of the RNA

c. 3'-5' triphosphate linkage at the 5’ end of the RNA

d. 3'-2' triphosphate linkage at the 3’ end of the RNA

e. 5'-5' triphosphate linkage at the 5’ end of the RNA

e. 5'-5' triphosphate linkage at the 5’ end of the RNA

89

During splicing in precursor mRNA in mammalian cells, the first RNA cleavage step involves:

a. the covalent linkage of the branch site adenine to the 5’ end of the intron

b. covalent linkage of the 5’ end of the second exon with the 3’ end of the branch site

c. hydrogen bonding of the guanosine at the branch site with the 3’ exon end

d. hydrogen bonding of the adenine at the branch site with the 5’ intron

e. disulfide bridging of the 5’ and 3’ ends of the intron

a. the covalent linkage of the branch site adenine to the 5’ end of the intron

90

Eukaryotic tRNA molecules have a CCA sequence at their 3’ terminus because:

a. that sequence is the anticodon sequence

b. that sequence is added by a nucleotidyl transferase

c. that sequence is a signal sequence for RNA polymerase binding

d. that sequence is a termination signal for the RNaseD exonuclease

e. that sequence is required for an internal hairpin to form

b. that sequence is added by a nucleotidyl transferase

91

Tandem mass spectrometry can be used to find out:

a. the nucleotide sequence of an mRNA

b. the nucleotide sequence of a gene

c. the amino acid sequence of a protein

d. the composition of a multi-protein complex

c. the amino acid sequence of a protein

92

How many different reading frames are present in a DNA sequence?

a. one

b. two

c. three

d. six

e. none of the above

d. six

93

A microarray used to study gene expression is hybridized with:

a. total RNA from a specific cell type

b. protein from a specific cell type

c. cDNA from a specific cell type

d. PCR-generated oligonucleotides using genomic DNA templates

c. cDNA from a specific cell type

94

You are investigating a protein complex, and have isolated one protein and raised antibodies to it. You suspect it interacts directly with another protein. The easiest and fastest way to determine if the interaction does occur is to do a:

a. ChIP-chip

b. tandem mass spectrometry analysis

c. Western blot

d. immunoprecipitation

e. two-hybrid analysis

d. immunoprecipitation

95

What is the role of sigma factor?

            a.  it recognizes the termination signal

            b.  it stays associated with RNA polymerase at all times

            c.  it recognizes conserved sequences in the promoter

            d.  all these are roles of sigma factor.

            c.  it recognizes conserved sequences in the promoter

96

In E. coli cells, the level of cyclic AMP is determined by:

            a.  the presence of an F factor


            b.  the glucose concentration


            c.  the lactose concentration


            d.  the allolactose concentration

            e.  the total amount of cellular RNA

   b.  the glucose concentration


97

E. coli cells that are growing in a medium that is rich in glucose cannot be induced to express the enzyme β-galactosidase, even when lactose is added to the medium. This repression is due to:

            a.  irreversible binding of the lac repressor protein to the operator


            b.  failure of the transcription termination mechanism


            c.  induction of the lacI gene by glucose


            d.  failure of the Catabolite Activator Protein/cyclic AMP complex to bind the lac promoter

            e.  a conformational change in the lac repressor protein due to an interaction with glucose

d.  failure of the Catabolite Activator Protein/cyclic AMP complex to bind the lac promoter

98

Attenuation at the trp operon in E. coli occurs when:

            a.  translation and transcription become uncoupled

            b.  high tryptophan levels inhibit the binding of a repressor protein

            c.  low tryptophan levels increase the rate of RNA polymerase progression

            d.  high tryptophan levels allow the formation of a terminator stem-loop in the trpL mRNA

            e.  the tryptophan membrane transporter increases the rate of tryptophan import

d.  high tryptophan levels allow the formation of a terminator stem-loop in the trpL mRNA

99

Which of the following is NOT a common method of gene regulation in eukaryotes?

            a.  histone modification

            b.  attenuation

            c.  nucleosome spacing alterations

            d.  RNA processing

b.  attenuation

100

When RNA polymerase II initiates transcription:

            a.  TFIIA is the first transcription factor to bind the promoter.

            b.  a complex of basal transcription factors must assemble on the promoter.

            c.  RNA polymerase II binds to naked DNA

            d.  helicase must first unwind the DNA

  b.  a complex of basal transcription factors must assemble on the promoter.

101

Which of the following statements is NOT correct?

            a.  the consensus sequence for the eukaryotic polyadenylation signal is AAUAAA

            b.  the typical length of a poly A tail in humans is 200-250 nucleotides

            c.  polyA polymerase adds adenine nucleotides to the 5' end

            d.  polyadenylation is important for the stability of a mRNA

            e.  endonuclease cleavage occurs about 20 nucleotides downstream of the polyadenylation signal

c.  polyA polymerase adds adenine nucleotides to the 5' end

102

Which statement about pre-mRNA introns is true?

            a.  They are removed by cutting and joining the DNA

            b.  They are never removed; the ribosome skips them when making protein

            c.  They contain short consensus sequences at both ends

            d.  They are removed after the mRNA has been transported to the cytoplasm

            e.  None of these statements are true

c.  They contain short consensus sequences at both ends

103

Which statement about small nuclear ribonucleoprotein particles (snRNPs) is false?

            a.  They contain both RNA and protein components

            b.  They bind to specific sites in the pre-mRNA

            c.  They interact with Group I self-splicing introns

            d.  They interact with each other to form an active spliceosome

            e.  None of these statements are false

c.  They interact with Group I self-splicing introns

104

Transcription is similar to DNA replication in that it….

True/False

 1.  requires a DNA template

2.  requires a primer to initiate synthesis

3.  begins at specific sites in the genome

 4.  requires the step-wise formation of a multi-component complex to initiate

5.  synthesizes a new strand in the 5’ to 3’ direction

1. True

2. False

3. True

4. True

5. True

105

The following are DNA binding domains used in transcription factors:

True/False

1.  zinc finger

   2.  helix-turn-helix

  3.  basic domain

   4.  disulfide bridge

  5.  glutamine-rich domain

1. True

2. True

3. True

4. False

5. False

106

Indicate True or False for each statement about the Carboxy Terminal Domain of RNA polymerase II:

   1.  it is phosphorylated by TFIIH

     2.  its phosphates are removed when transcription elongation begins

     3.  capping factors bind when it is dephosphorylated

     4.  splicing factors bind when it is phosphorylated

     5.  polyadenylation factors bind when it is phosphorylated

1. True

2. False

3. False

4. True

5. True

107

For which of the following experiments would a DNA microarray be useful?

  1.  identifying the binding site for a transcription factor

  2.  determining if a transition mutation occurred in a gene during replication

  3.  determining which genes are down-regulated in response to heat shock

   4.  identifying the site of a DNA inversion

  5.  distinguishing between two closely related bacterial subspecies

1. True

2. False

3. True

4. False

5. True

108

An E. coli strain contains a plasmid with a copy of the Lac operon.  It has the genotype lacIlacO- lacZlacYlacA+.  On the E. coli chromosome, the Lac operon has the genotype lacIlacOlacZlacYlacA-.  Indicate whether each of the following proteins will be present at a very high level or a low level in the absence of lactose and glucose, or in the presence of lactose

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109

a) Underline the Pribnow Box in the sequence.

b) Circle the -35 promoter recognition sequence

c) Place a star (*) above the nucleotide pair that occurs at the +1 transcription start site

d) Based on your analysis of this promoter region, which strand, top or bottom, will be the template strand?

                         The template strand is the bottom strand

e) Based on your analysis of this promoter region, in which direction, left or right, will transcription proceed?

                        Transcription will proceed to the right

e) Write the first eight nucleotides that will make up the beginning of the mRNA made from this promoter:

                        5’ AGGGCUUG… 3’

            (most common mistake = using T instead of U)

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