Chapter 16: Control of Gene Expression Flashcards

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1
Q

Controlling gene expression is often accomplished by controlling ______ _______

A

transcription initation

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2
Q

_______ ________ bind to DNA, modulate binding of RNA polymerase to promoter

A

regulatory proteins

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3
Q

___________ organisms regulate gene expression in response to their environment

A

prokaryotic

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4
Q

________ cells regulate gene expression to maintain a constant internal environment in the organism

A

eukaryotic

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5
Q

What type of regulation is this
- chromatin remodeling to make genes accessible for transcription
-regulatory events at a gene’s promoter and regulatory sequences

A

transcriptional regulation

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6
Q

What type of transcription is this
- variations in pre-mRNA processing
-removal of making proteins
-variations in rate of mRNA breakdown
-RNA interference

A

posttranscriptional regulation

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7
Q

What type of regulation is this
- variations in rate of initiation of protein synthesis

A

translational regulation

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8
Q

What type of regulation is this
- variations in rate of protein processing
-removal of making segments
-variations in rate of protein breakdown

A

posttranslational regulation

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9
Q

What type of regulation determines which genes are transcribed?

A

transcriptional

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10
Q

What type of regulation determines types and availability of mRNAs to ribosomes?

A

posttranscriptional

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11
Q

What type of regulation determines the rate at which proteins are made?

A

translational

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12
Q

What type of regulation determines the availability of finished proteins?

A

posttranslational

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13
Q

Gene expression is often controlled by _____ _____ binding to specific DNA sequences

A

regulatory proteins

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14
Q

______ ______ gain access to the bases of DNA at the major groove

A

regulatory proteins

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15
Q

Regulatory proteins possess ____-_____ motifs

A

DNA-binding

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16
Q

What are the two things regulatory proteins can do?

A
  1. block transcription by preventing RNA polymerase to bind
  2. stimulate transcription by facilitating RNA polymerase binding to promoter
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17
Q

Within the ____ groove, nucleotides’ hydrogen bond donors and acceptors are accessible

A

major

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18
Q

T or F: The unique pattern of accessibility for each base pair combination enables proteins to read the sequence without unwinding DNA

A

True

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19
Q

What are the regions of regulatory proteins that bind to DNA called?

A

DNA-binding motifs

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20
Q

What is the two a-helical segments linked by a nonhelical segment called?

A

Helix-turn-helix motif

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21
Q

What is a special class of helix-turn-helix and is critical in eukaryotic development?

A

Homeodomain

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22
Q

What type of motif uses zinc atoms to coordinate DNA binding?

A

Zinc finger

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23
Q

What type of motif has one subunit that interacts with a similar region on another subunit forming a zipper-like connection

A

Leucine zipper motif

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24
Q

(prokaryotic regulation) ______ _____ can be positively or negatively controlled

A

transcription initiation`

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25
Q

What type of control increases freqeuncy?

A

positive

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26
Q

In positive control _______ enhance binding of RNA polymerase to promoter?

A

activators

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27
Q

What type of control decreases frequency?

A

negative control

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28
Q

In negative control ____ bind to regulatory sites on DNA called operators that prevent or decrease initiation frequency

A

repressors

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29
Q

_____ molecules can act on both repressors and activators

A

effector

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30
Q

______ cells often respond to their environment by changes in gene expression

A

prokaryotic

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31
Q

genes involved in the same metabolic pathway are organized in ______

A

operons

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32
Q

In _______ enzymes for a certain pathway are produced in response to a substrate

A

induction

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33
Q

______ is capable of making an enzyme by does not

A

repression

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34
Q

____ ______ encodes proteins necessary for the use of lactose as an energy source

A

lac operon

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35
Q

What are the three genes in the lac operon?

A

LacZ, lacY, lacA

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36
Q

What gene is linked to the rest of the lac operon?

A

the lac repressor (lacl)

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37
Q

The promoter for the gene, the gene repressor protein, CAP-binding site, the promoter for the operon, and the operator are all in the _____ region

A

regulatory

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38
Q

if lactose is absent the lac operon is _____

A

repressed

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39
Q

if lactose is absent the lac operon is ______

A

induced

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40
Q

What is the mechanisms for the preferential use of glucose in the presence of other sugars?

A

glucose repression

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41
Q

What is the catabolic activator protein (CAP)?

A

an allosteric protein with cAMP as effector

42
Q

The presence of glucose inhibits the transport of lactose into the cell which is ____ exclusion

A

inducer

43
Q

If glucose is low the inducer is present so _____ activated

A

Promoter

44
Q

If glucose is high, the inducer is ____

A

absent

45
Q

____ operon encodes genes for the biosynthesis of tryptophan

A

trp

46
Q

T or F: the trp operon is not expressed when the cell contains sufficient amounts of tryptophan

A

True

47
Q

The trp repressor is a helix-turn- helix protein that binds to the operator site located _____ to the trp promoter

A

adjacent

48
Q

The trp operon is ____ regulated by the trp repressor

A

negatively

49
Q

When trytophan levels fall, the ____ cannot bind to the operator

A

repressor

50
Q

When the tryptophan is absent the operon is ______

A

derepressed

51
Q

If the tryptophan is present then the operon is ____

A

repressed

52
Q

tryptophan binding _____ the distance between the two recognition helices

A

increases

53
Q

Since the distance is increased between the recognition helices by tryptophan, the repressor can then fit snugly into two adjacent portions of the ______ groove in DNA

A

major

54
Q

What are the major differences from prokaryotic control of transcription and eukaryotic control of transcription?

A
  1. Eukaryotes have DNA organized into chromatin
    2.Eukaryotic transcription occurs in nucleus while translation occurs in cytoplasm
55
Q

General transcription factors are necessary for the assembly of a ______ ______ and recruitment of RNA polymerase II to a promoter

A

transcription apparatus

56
Q

What sequence does TFIID recognize?

A

The TATA box

57
Q

After TFIID binds what other transcription factors bind?

A

TFIIE< TFIIF, TFIIA, TFIIB, TFIIH

58
Q

General transcription factors can initiate synthesis at a _____ level

A

basal

59
Q

Specific transcription factors act in a tissue- or time-dependent manner to stimulate _____ levels of transcription than the basal level

A

higher

60
Q

Each specific transcription factor consists of a ____-____ domain and a _____ _____ domain that interacts with the transcription apparatus

A

DNA-binding, separate activating

61
Q

T or F: in specific transcription factors, the domains are independent in the protein

A

True

62
Q

______ form the binding sites for general transcription factors

A

promoters

63
Q

_______ are the binding site of the specific transcription factors

A

enhancers

64
Q

_______ can act over large distances by bending DNA to form loop to position enhancer closer to promoter

A

enhancers`

65
Q

______ and ______ are also required for the function of transcription factors

A

coactivators, mediators

66
Q

_______ and _____ bind to transcription factors and bind to other parts of the transcription apparatus

A

coactivators and mediators

67
Q

_______ are essential to some but not all transcription factors

A

mediators

68
Q

_______ can be used with multiple TF (transcription factors)

A

coactivators

69
Q

______ structure is selectively modulated to allow transcription

A

chromatin

70
Q

alternations in chromatin structure are thought to be the basis for _______

A

epigenetics

71
Q

T or F: heritable changes in phenotype not due to changes in DNA sequence

A

true

72
Q

_______ alternations must persist in the absence of the initating stimulus, and must be inherited through cell division

A

epigenetic

73
Q

High levels of _____ _______ correlate with inactive genes

A

DNA methylation

74
Q

_____-_____ gene expression seen in genomic imprinting is at least partially due to DNA methylation

A

Allele-specific

75
Q

T or F: Mammalian females inactivate one X chromosome as a form of dosage compensation

A

True

76
Q

How many possible histones can be modified

A

four

77
Q

What are the possible modifications to histones?

A

acetylation, methylation, phosphorylation,

78
Q

In general _____ is correlated iwth active sites of transcription

A

acetylation

79
Q

Some transcription coactivators have been shown to be _____ _____

A

histone acetylases

80
Q

Transcription is increased by removing higher order _____ structure that would prevent transcription

A

chromatin

81
Q

_______ _______ remove acetyl groups from histones

A

histone deacetylases

82
Q

Control of gene expression usually involves the control of _____ initation

A

transcription

83
Q

What are posttranscriptional regulation mechanisms?

A
  1. small RNAs
    2.Alternative splicing
  2. RNA editing
    4.mRNA degradation
84
Q

lin-4 mutant alters developmental timing in ______

A

C. elegans

85
Q

_____ does not encode a protein product, instead, it encodes two small RNA molecules

A

lin-4

86
Q

_____ RNA acts as a transcriptional repressor of an mRNA

A

lin-4

87
Q

_____ production begins with RNA pol II producing a transcript called the pri-mRNA

A

miRNA

88
Q

miRNA folds back on itself to form a stem-and loop-structure which is cleaved by _____ to form pre-miRNA

A

drosha

89
Q

pre-miRNA exported from the nucleus and cleaved by ____ to produce a short double stranded RNA containing the miRNA

A

dicer

90
Q

miRNA loaded into a protein complex called an ____

A

RISC (RNA induced silencing complex)

91
Q

RISC includes the _____-____ protein Ago, which interacts with the miRNA

A

RNA-binding

92
Q

_____ is targeted to repress the expression of genes based on sequence complementarity to the miRNA

A

RISC

93
Q

RNA _______ refers to small RNA gene silencing

A

interference

94
Q

siRNA arise from long _____-_______ RNA

A

double-stranded DNA

95
Q

with siRNA production, the ______ cuts yield multiple siRNA which are loaded into RISC

A

Dicer

96
Q

Biogenesis of both miRNA and siRNA involves cleavage by _____ and incorporation into a _____ complex

A

Dicer, RISC

96
Q

target mRNA is cleaved by _______ containing RISC

A

siRNA

96
Q

RNA silencing pathways have been implicated in the formation of _______ in different organisms

A

heterochromatin

97
Q

_____ repress genes different from their origin

A

miRNA

97
Q

endogenous _____ tend to repress genes they were derived from

A

siRNAs

98
Q

The editing of mature _____ transcripts can produce an altered mRNA that is not truly encoded in the genome

A

mRNA

99
Q

In ______, RNA editing involves chemical modification of base to change its base-pairing properties

A

mammals