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BIOL 1105 > 13: Regulation of Gene Expression > Flashcards

13: Regulation of Gene Expression Flashcards

Module 3, Lesson 2

1
Q

The process of converting genetic information into a genetic product (usually a protein) is…

A

Gene expression

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2
Q

Prokaryotes regulate their gene expression to…

A

Respond to environmental changes

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3
Q

Eukaryotes regulate their gene expression to…

A

Progress through developmental stages and maintain homeostasis

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4
Q

List the three means by which organisms can regulate gene expression.

A
  1. Transcriptional regulation
  2. Post-transcriptional regulation
  3. Post-translational regulation
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5
Q

Which method(s) of regulation can only occur in eukaryotes?

A

Post-transcriptional

because this occurs as mRNA is moved out of the nucleus, which prokaryotes do not have

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6
Q

The first opportunity for cells to control gene expression is…

A

Transcriptional regulation

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7
Q

The most common form of regulation in cells is…

A

Transcriptional

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8
Q

Transcriptional regulation depends on…

A

RNA polymerase interacting with DNA

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9
Q

Transcriptional regulation is controlled by…

A

Binding proteins
(“transcription factors”)

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10
Q

The ____ contains the binding site for regulatory proteins that affect the cell’s ability to perform transcription.

A

Promoter

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11
Q

The region of the promoter where RNA polymerase binds to the DNA is the…

A

Core promoter

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12
Q

Proteins that affect the ablity of RNA polymerase to bind to the promoter or start transcription are…

A

Regulatory proteins

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13
Q

True or false:

In eukaryotic cells, each gene has its own promoter sequence.

A

True

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14
Q

True or false:

In prokaryotes, a single promoter can control multiple genes.

A

True

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15
Q

Regulatory proteins that help recruit RNA polymerase to start transcription are called…

A

Transcriptional activator proteins

(or simply “activator proteins”)

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16
Q

The process by which a regulatory protein promotes transcription is…

A

Positive control

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17
Q

A protein that binds to a gene in such a way as to prevent RNA polymerase from binding is called a…

A

Transcriptional repressor protein

(or simply “repressor protein”)

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18
Q

The process by which a regulatory protein inhibits transcription is…

A

Negative control

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19
Q

True or false:

Genes can have positive or negative control, but not both.

A

False

A gene or operon can have positive control, negative control, or both.

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20
Q

A cluster of genes with related functions that are controlled by a single promoter is called a(n)…

A

Operon

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21
Q

Prokaryotes are able to respond quickly to environmental changes because…

A

Their genes are organized into operons

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22
Q

List the three regions that an operon may have.

A
  1. Core promoter
  2. Activator binding site
  3. Operator
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23
Q

The ____ region of an operon is bound by the sigma factor of RNA polymerase.

A

Core promoter

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24
Q

True or false:

All operons have a core promoter region.

A

True

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25
Q

The DNA binding site for an activator protein is called the…

A

Activator binding site

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26
Q

True or false:

All operons have an activator binding site.

A

False

Only operons that exhibit positive control can have activator binding site(s).

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27
Q

The DNA binding site for a repressor protein is called a(n)…

A

Operator

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28
Q

True or false:

All operons have an operator.

A

False

Only operons that exhibit negative control can have operator(s).

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29
Q

In prokaryotes, the proteins needed for lactose metabolism are encoded in the…

A

lac operon

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30
Q

What type(s) of control does the lac operon exhibit?

A

Positive and negative

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31
Q

In the lac operon, the CAP activator promotes transcription when…

A

Lactose is present

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32
Q

In the lac operon, the lac repressor protein inhibits transcription when…

A

No lactose is present

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33
Q

The lac operon can only perform transcription when…

A

Lactose is present AND glucose is absent

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34
Q

What happens in a lac operon when both lactose and glucose are present?

A

The lac repressor is released, but the CAP activator does not bind to the DNA.

because glucose is the cell’s preferred food source

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35
Q

The trp operon contains all the genes needed to produce…

A

Tryptophan
(an amino acid)

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36
Q

What type(s) of control does the trp operon exhibit?

A

Negative

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37
Q

The trp operon does not perform transcription when…

A

Tryptophan is present in the environment

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38
Q

The trp operon performs transcription when…

A

No tryptophan can be acquired from the environment

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39
Q

How does the trp operon exhibit negative control?

A

When tryptophan is present, it binds the the trp repressor protein, enabling it to bind to the operator sequence.

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40
Q

____ occurs when transcription is stimulated by molecules in the environment.

A

Induction

41
Q

____ occurs when transcription is inhibited by molecules in the environment.

A

Repression

42
Q

In addition to positive and negative control, the lac operon exhibits…

A

Induction

(the presence of lactose causes the lac repressor protein to be released from the DNA)

43
Q

In addition to negative control, the trp operon exhibits…

A

Repression

(the presence of tryptophan causes the trp repressor protein to bind to the DNA)

44
Q

Induction and repression occur when…

A

An external molecule causes or stops transcription by interacting with a regulatory protein

45
Q

Positive and negative control refers to…

A

The type of protein that regulates transcription

46
Q

List the two types of transcription factors.

A
  1. General
  2. Specific
47
Q

True or false:

General transcription factors are only found in eukaryotes.

A

True

48
Q

Eukaryotes require general transcription factors in order for…

A

The minimum (basal) amount of transcription to occur

49
Q

List three ways eukaryotes can use general transcription factors to regulate transcription.

A
  1. Changing the availability of the transcription factors
  2. Altering the TFs’ ability to bind to DNA
  3. Altering the TFs’ ability to interact with RNA polymerase
50
Q

____ are needed to increase transcription past the basal level.

A

Specific transcription factors

51
Q

True or false:

Specific transcription factors are found in both prokaryotes and eukaryotes.

A

True

52
Q

True or false:

A specific transcription factor will always bind at or near the core promoter.

A

False

Eukaryotes in particular may utilize other binding sites.

53
Q

Some specific transcription factors bind to DNA regulatory regions called…

A

DNA enhancer elements

54
Q

Why do specific transcription factors not always bind to the core promoter in eukaryotes?

A

Their genomes are much bigger.

55
Q

In eukaryotes, DNA and histone proteins are packaged into bead-like structures called…

A

Nucleosomes

56
Q

Nucleosomes are then assembled into…

A

A chromatin structure

57
Q

Why do eukaryotes package their DNA?

A

So that all the DNA is able to fit into the nucleus.

58
Q

When DNA becomes wound around histone proteins, it becomes ____ for transcription machinery to access it.

A

Harder

59
Q

____ can be modified to change how tightly DNA is wound around them.

A

Histone proteins

60
Q

____ is a process that loosens DNA by adding an acetyl group.

A

Acetylation

61
Q

The structure of nucleosomes can be altered by…

A

ATP-dependent enzymes

62
Q

List three ways in which ATP-dependent enzymes can change nucleosomes.

A
  1. Sliding
  2. Moving up/down DNA
  3. Remodeling
63
Q

Remodeling involves altering…

A

How DNA interacts with histone proteins

64
Q

____ regulation occurs while the cell is preparing mRNA for translation.

A

Post-transcriptional regulation

65
Q

Which type of gene regulation only occurs in eukaryotes?

A

Post-transcriptional

66
Q

List four methods of post-transcriptional gene regulation.

A
  1. mRNA alternative splicing
  2. Inhibition of transport from nucleus
  3. Inhibition of translation
  4. mRNA regulation by small RNAs
67
Q

Alternative splicing is the process of…

A

Causing one mRNA to code for different proteins

68
Q

Some mRNA sequences can be spliced in multiple ways, enabling them to…

A

Code for more than one protein

69
Q

Alternative splicing has been observed in the…

A

Thyroid and hypothalamus

70
Q

It is believed that only around ____% of the mRNA produced is exported and translated.

A

5%

71
Q

List two ways that the cell can limit the amount of mRNA that is translated after it has left the nucleus.

A
  1. Limiting the availability of proteins needed for translation
  2. Producing proteins that prevent specific mRNA from being translated
72
Q

List the two classes of small RNAs that can interfere with mRNA translation.

A
  1. Micro RNAs (miRNAs)
  2. Small-interfering RNAs (siRNAs)
73
Q

Micro RNAs are formed when a single-stranded RNA folds to make a small segment of…

A

Double-stranded RNA

74
Q

Micro RNA strands are…

A

Self-complementary

75
Q

Micro RNAs are usually encoded in the…

A

Genome

76
Q

Small-interfering RNAs are made from long segments of double-stranded RNA that are…

A

Cut into small segments

77
Q

List two ways in which siRNAs can be formed.

A
  1. Produced by the cell through pairing of 2 mRNAs
  2. Introduced from the environment
78
Q

Small RNAs interact with proteins to form a complex called…

A

RISC

79
Q

After binding to the complementary region on a target mRNA, the proteins in RISC…

A

Block translation or degrade the mRNA

80
Q

____ is a research method that introduces specific segments of double-stranded RNA to selectively control gene expression.

A

RNA interference
(RNAi)

81
Q

RNAi allows researches to analyze the effects of ____ on an organism.

A

Gene loss

82
Q

Post-translational gene regulation involves…

(two items)

A
  1. Modification of proteins
  2. Degradation of proteins
83
Q

Post-translational regulation occurs…

A

After mRNA has been made into proteins

84
Q

List three methods of modifying proteins.

A
  1. Adding/removing a phosphate group
  2. Adding carbohydrates
  3. Adding lipid groups
85
Q

The addition or removal of a phosphate group is especially important for…

A

Enzymes

86
Q

The addition or removal of a phosphate group is called…

A

Phosphorylation or dephosphorylation

87
Q

The addition of carbohydrates is especially important for…

A

Cell identity proteins

88
Q

The addition of a carbohydrate is called…

A

Glycosylation

89
Q

The addition of lipid groups is especially important for…

A

Anchor proteins in the cell membrane

90
Q

Cells can systematically target and degrade proteins by…

A

Adding ubiquitin

91
Q

After a protein has been ubiquinated…

A

It is broken down into polypeptide fragments by the proteasome

92
Q

True or false:

The ubiquitin is also degraded by the proteasome.

A

False

It is cleaved from the protein and released to be used again

93
Q

Because of regulation, gene expression is…

A

Very tightly controlled

94
Q

Transcriptional regulation controls…

A

Which genes are transcribed

95
Q

Transcriptional regulation is performed by…

A

Transcription factors and the accessibility of DNA

96
Q

Post-transcriptional regulation controls…

A

Which genes are translated

97
Q

Post-transcriptional regulation is performed by…

A

mRNA processing and translation inhibition

98
Q

Post-translational regulation controls…

A

The activity of translated proteins

99
Q
A

BIOL 1105 (26 decks)

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