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Flashcards in midterm 3 Deck (126):
1

How does binding of the lac repressor to the lac operator block transcription initiation?

lac repressor binding blocks RNA polymerase from interacting with DNA at the start site

2

Which of the following is not an example of a transcription factor DNA-binding domain?

glycine zipper

3

In RNA interference experiments, siRNAs homologous to known mRNAs inhibit expression of the proteins by what mechanism?

they form double-stranded RNA molecules that get degraded in the cytoplasm

4

The lac operon in E. coli is regulated by lactose, which _______ of transcription

binds an repressor

5

Steroid hormone receptors recognize and bind to specific DNA sequences by ______ domains

zinc finger

6

Which of the following both stabilizes and increases the efficiency of translation of an mRNA?

addition of Poly A to 3' end and addition of 7-methylguanoisne cap

7

Ferritin expression is stimulated by iron because iron

stimulated the dissociation of a translational inhibitor from the ferritin mRNA

8

What is the function of karyopherins?

they transport macromolecules into and out of the nucleus

9

N-linked glycosylation at an Asn-X-Ser/Thr consensus sequence adds ____ sugar(s) in a single step to the protein.

14

10

Processing of RNA transcripts occur

with tRNA, rRNA, and mRNA transcripts

11

The 7-methyl guanosine cap on mRNA is required for

protecting an mRNA from exonuclease attack and initiation of translation of the mRNA

12

Suppose that a gene has three exons and two introns in the following order: 5'-exon 1 - intron 1 - exon 2- intron 2 - exon 3-3' Which of the following could not result from alternative splicing in this gene?

5'-exon 2-exon 1-3'

13

The form of apolipoprotien B (Apo-B) produced by the intestine is shorter than the Apo-B produced by the liver, The intestine produces a smaller protein by

shortening the mRNA of the forming polypeptide chain

14

E. coli contains about ___ different tRNAs that code for ___different amino acids.

40;20

15

The primary function of rRNAs in the ribosome is

to catalyze peptide bond formation

16

Antibiotics are powerful medications that inhibit the growth of bacteria. They work at a variety of levels, but many target the process of protein synthesis in the bacterial cell. In the developing of an antibiotic, which of the following would be an effective strategy or target for the drug?

all of the above

17

Which of the following it not associated with translation regulation?

autolytic degradation of the mRNA by folding back on itself

18

The nuclear lamina binds to

both the inner nuclear envelope membrane and chromatin

19

The directionality of the nuclear protein import is dertermined by

an unequal distribution of Ran/GTP

20

an important step in the import of the transcription factor NFkB into the nucleus is regulated by

protease

21

Chromosomes are distributed in the nucleus

in distinct territories

22

Ribosomes contain one copy of each 5.8s, 18S, 28S rRNA. The major mechanism ensuring that each is

the grouping of the DNA sequences encoding each rRNA into a single rRNA gene

23

The nuclear localization signal is recognized by and binds to which protein in the process of nuclear protein import?

importin

24

Nuclear localization signals were first identified by Alan Smith and his colleagues in the protein

SV40 T antigen

25

"Classical" nuclear localization signals are composed primarily of

basic amino acids

26

When compared to polypeptides synthesized in vitro on free ribosomes, the polypeptides synthesized from the same mRNA on microsome-bound ribosomes often are

smaller

27

The proteins shaped like a "double chamber" that are involved in protein folding are called____

chaperonin proteins

28

When Tetrahymena 28S rRNA is incubated in the absence of proteins, it undergoes

self-splicing

29

Through the process of ____, cells can produce different transcription factors from the same gene that are either gene activators or repressors.

alternative splicing

30

The factor that escorts the aminoacyl tRNA to the eukaryotic ribosome and then releases it with GTP hydrolysis following the correct codon-anticodon base pairing is____

eEF-1alpha

31

Initial steps in the functional assembly of snRNPs occur in the ____

cytoplasm

32

The directionality of nuclear proteins is determined by an unequal distribution of

Ran/GTP

33

The first step in the initiation of protein synthesis is the binding of initiation factors to the small ribosomal subunit.

true

34

The transmission of information that is not contained within the sequence of DNA to daughter cells at cell division is called epigenetic inheritance

true

35

The lac operon is regulated by the binding of an enhancer to sequences just upstream from the promoter

false

36

The predominant RNA synthesized by eukaryotic RNA polymerase II is rRNA

false

37

The correctly folded three-dimensional configuration of a protein is determined primarily by the primary sequence of its amino acids.

true

38

Monomeric G proteins, such as Ras and several elongation factors, are usually in the active state when a molecule of GDP is bound to them.

false

39

Eukaryotic ribosomes recognize and initially bind to a Shine-Dalgarno sequence on the mRNA?

false

40

The nuclear envelope is continuous with the rough ER

true

41

For proteins that normally are nuclear, deletion of the nuclear localization signal and injection of protein into the cytoplasm of cultured cells will result in localization in the cytoplasm

true

42

Chromatin that contains sequences that are transcribed is called heterochromatin

false

43

In prokaryotes, sigma factors are necessary for

specific binding to certain promoters

44

The lac operon in E. coli is regulated by lactose, which

inactivates a repressor of transcription

45

E. coli preferentially utilizes glucose for energy. However, in the absence of glucose, genes that can metabolizes alternative sugars are activated. Low glucose

elevates cAMP through adenylyl cyclase that binds to and activates CAP no effectively increase transcription rates of genes that metabolize alternative sugars

46

What of the following is not part of the transcription complex?

RFC

47

Which of the following statements about cis-acting elements is true?

all of the above

48

A reporter gene is used to

identify regulatory sequences from the upstream regions of other genes

49

Which of the following best describes the ability of an enhancer to mediate transcription from very distant sites?

looping of the DNA can occur, allowing the transcription factor to get into the proximity of the RNA polymerase

50

Which of the following is not involved in the tissue-specific expression of the immunoglobin heavy-chain gene?

RNA polymerase II

51

Which of the following is not involved in relieving transcriptional repression imposed by chromatin?

DNA methylation

52

Which of the following experimental approaches is least likely to be used in identifying transcription factor binding sites?

Northern blotting

53

Which of the following is not an example of a transcription factor DNA- binding domain?

acidic

54

A ribozyme is defined as an enzyme

in which an RNA molecule is responsible for the catalytic activity

55

Which of the following both stabilizes and increases the efficiency of translation of an mRNA?

addition of a 7-methylguanosine cap

56

The consensus sequence for poly(A) addition is

AAUAAA

57

Which process involves two transesterification reactions?

splicing

58

Which of the following does not require protein enzymes?

excision of group II introns

59

microRNAs play a key role in which of the following?

translation repression

60

Which of the following statements regarding tRNAs is false?

all tRNAs have a CACsequence at their 3' terminus

61

The function of aminoacyl tRNA synthetases is to

covalently attach amino acids to their corresponding tRNA molecules

62

The first amino acid of prokaryotic polypeptides is

methionine

63

The initiator codon in prokaryotes is

recognized via the Shine-Dalgarno sequence

64

Which of the following about translational regulation of ferritin is false?

the iron response element is a unique sequence of amino acids near the amino terminus of the growing polypeptide

65

The major pathway for molecules to pass into and out of the nucleus is through

nuclear pore complexes

66

Calreticulin assists in folding glycoproteins that contain one____residue

glucose

67

The nuclear localization signal is typically a___, rich in the amino acids____.

short sequence, Lys and Arg

68

Which of the following statements about snRNAs is true?

they are synthesizes in the nucleus, move to the cytoplasm to pick up proteins to become functional, and then return to the nucleus

69

Eukaryotic ribosomes leave the nucleus as

40S and 60S ribosomal subunits

70

In translation, mRNAs are read in _____ direction, and polypeptide chains are synthesized from the ____ends

5' to 3', amino to carboxyl

71

Aminoacyl tRNA synthetases are enzymes that

attach amino acids to specific transfer RNAs

72

Eukaryotic ribosomes recognize and initially bind to what structure on the mRNA?

the 7-methylguanosine cap

73

cAMP activates cAMP-dependent protein kinase by

binding regulatory subunits and inducing their release from the catalytic subunits

74

The primary function of rRNAs in the ribosome is

to catalyze peptide bond formation

75

Which of the following statements about translation initiation is false?

in prokaryotes, ribosomes often bind the mRNA and can scan 5' or 3' until recognizing a Shine-Dalgarno sequence

76

A proteasome is a

multisubunit protease complex that degrades ubiquitinated proteins

77

Which of the following statements about transmembrane proteins is true?

the usually have one or more alpha helices spanning the membrane bilayer

78

Underlying the nuclear envelope is____, a fibrous meshwork composed of proteins called_____.

nuclear lamina, lamins

79

Receptor-dependent protein transport into the nucleus requires the recognition of_____ on the cargo protein.

NLS

80

Initiation sequence in bacterial mRNAs are preceded by a specific sequence called a _____ sequence, while initiation sequence in eukaryotic mRNAs are often preceded by a consensus sequence call a ___sequence.

Shine-Dalgarno, Kozak

81

The enzyme that catalyzes the breakage and reformation of disulfide bonds between cysteine residues of proteins is_____

PDI

82

Elongation requires ____GTP per amino acid.

2

83

The nuclear pore complexes provide the only known routes through which molecules can travel between the nucleus and the cytoplasm of interphase cells.

true

84

Ribosomal proteins are synthesized in the nucleolus and then assembled onto rRNAs

false

85

An 80S eukaryotic ribosome is made up of one large 50S subunit and one small 30S subunit

false

86

Translation can be regulated by proteins that bind to the 3' untranslated regions of mRNAs

true

87

Individual chromosomes occupy discrete territories within the nucleus

true

88

Cells contain 64 tRNAs, with one anticodon for each codon

false

89

Messenger RNAs are transported through the nuclear pores as ribonucleoprotein particles

true

90

Some chaperons were originally known as heat-shock proteins because they are expressed in cells subjected to high temperatures and facilitate the refolding of denatured proteins

true

91

All molecules that are in the nucleus are transported therein via a process that requires ATP

false

92

SnoRNP particles contain RNA sequences complementary to rRNA sequences

true

93

Which of the following does not take place in the nucleus?

translation

94

The outer nuclear membrane is contiguous with the

ER

95

The fibrous proteins underlying the inner nuclear membrane are

lamins

96

The nuclear pore complex of proteins is estimated to have a mass

about 30 times that of a ribosome

97

Classical nuclear localization signals are composed primarily of

basic amino acids

98

What is the function of karyopherins?

they transport macromolecules into or out of the nucleus

99

mRNA molecules are exported from the nucleus to the cytoplasm via

a recruited protein complex

100

Initial steps in the functional assembly of snRNPs occur in the

cytoplasm

101

Ferritin expression is stimulated by iron because iron

stimulates the dissociation of a translational inhibitor from the ferritin mRNA

102

Self-splicing was discovered in studies of

pre-rRNA in tetrahymena

103

The form of apolipoprotien B (Apo-B) produced by the intestine is shorter than the Apo-B produced by the liver, The intestine produces a smaller protein by

including fewer exons in the mRNA by alternative splicing

104

The RNA components of the splicesome are five different

small nuclear RNAs

105

Processing of RNA transcripts occurs

with tRNA, rRNA, and mRNA transcripts

106

The formation of peptide bonds is catalyzed by which protein of the bacterial ribosome

23S rRNA

107

The factor that escorts the aminoacyl tRNA to the eukaryotic ribosome and then releases it with GTP hydrolysis following the correct codon-anticodon base pairing is

eIF-1

108

Termination of translation and release of the polypeptide chain occurs when

a protein release factor binds to the termination codon

109

Phosphorylation of eukaryotic initiation factors 2 and 2B

allows them to initiate translation

110

Monomeric G proteins, such as Ras and several elongation factors, are usually in the active state when a molecule of ____ is bound to them.

GTP

111

By restricting the traffic of proteins and RNA across the nuclear envelope eukaryotic cells can regulate ___ in unique ways.

translation and transcription

112

Which of the following is not involved in the transport of RNAs out of the nucleus?

small RNAs crossing by passive diffusion

113

As they emerge from the ribosome, signal sequences are recognized and bound by a

SRP

114

Messenger RNAs have varying half-lives in the cytoplasm, and those differences are usually due to differences in the sequences near the 3' end of the RNA

true

115

RNA editing refers to RNA processing events (other than splicing) that alter the protein-coding sequences of some mRNAs

true

116

Ribozymes are critical for both ribosomal RNA processing and mRNA translation

true

117

The 3'-OH group of an A reside within the intro of pre-mRNAs is required for the formation of the lariat structure seen during mRNA splicing

false

118

Eukaryotic mRNAs have a 7-methylguanosine cap on their 3' end

false

119

One molecule of GTP is split in the process of loading one amino acid onto its tRNA

false

120

MicroRNAs can regulate translation by targeting proteins that can either cleave an mRNA or repress its translation

true

121

The nuclear pore complexes provide the only known routes through which large molecules can travel between the nucleus and the cytoplasm of interphase cells

true

122

The activity of some proteins is regulated based on whether they can (or cannot) be imported into the nucleus

true

123

ribosomal proteins are synthesized in the nucleolus and then assembled onto rRNAs

false

124

Receptor-dependent protein transport into the nucleus requires the recognition of ____ on the cargo proteins.

NLS

125

Cytoplasmic degradation of most eukaryotic mRNA is initiated by shortening of their

Poly-A tail

126

Translation is initiated by the binding of methionyl tRNA and the mRNA to the ___subunit, after which the other subunit joins the complex.

40S