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BIO 220 > Chapter 7 Control of Gene Expression > Flashcards

Chapter 7 Control of Gene Expression Flashcards

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Biology 101 flashcards
1
Q

Depends on changes in the gene expression rather than on any changes in the nucleotide sequence of the cell’s genome

A

Cell differentiation

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2
Q

The cell types in a multicellular organism become different from one another because

A

They synthesize and accumulate different sets of RNA and protein molecules

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3
Q

A cell can control the proteins it makes by (6 controls)

A
  1. Transcriptional control
  2. RNA processing control
  3. RNA transport and localization control
  4. Translational control
  5. mRNA degradation control
  6. Protein activity control
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4
Q

Controlling when and how often a given gene is transcribed

A

Transcriptional control

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5
Q

Controlling how the RNA transcript is spliced or otherwise processed

A

RNA processing control

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6
Q

Selecting which completed mRNAs in the cell nucleus are exported to the cytosol and determining where in the cytosol they are localized

A

RNA transport and localization control

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7
Q

Selecting which mRNAs in the cytoplasm are translated by ribosomes

A

Translational control

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8
Q

Selectively destabilizing certain mRNA molecules in the cytoplasm

A

mRNA degradation control

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9
Q

Selectively activating, inactivating, degrading, or compartmentalizing specific protein molecules after they have been made

A

Protein activity control

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10
Q

No question

A
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11
Q

How does a cell determine which of its thousands of genes to transcribe?

A

The transcription of each gene is controlled by a regulatory region of DNA relatively near the site where transcription begins

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12
Q

Some regulatory regions are simple and act as

A

Switches thrown by a single signal

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13
Q

Other regulatory regions are complex and resemble

A

Tiny microprocessors, responding to a variety of signals in order to switch their neighboring gene on or off

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14
Q

*Switching devices are found in all cells that are composed of two types of fundamental components

A
  1. Short stretches of DNA of defined sequence

2. gene regulatory proteins that recognize and bind to this DNA

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15
Q

Regulator encoded by a bacterial virus

A

Lambda repressor

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16
Q

Shuts off the viral genes enables the viral genome to remain a silent passenger in the bacterial chromosome

A

Lambda repressor

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17
Q

No question

A
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18
Q

*Turns off the production of the proteins responsible for lactose metabolism when this sugar is absent from the medium

A

Lac repressor

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19
Q

The expression of many genes is regulated by

A

The available food in the environment

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20
Q

Manufacture the amino acid tryptophan

A

Five E. coli genes that code for enzymes

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21
Q

Genes that are adjacent to one another on the chromosome and are transcribed from a single promoter as one long mRNA molecule

A

Operon

22
Q

When tryptophan is present in the growth medium and enters the cell

A

The cell no longer needs these enzymes and shuts off their production

23
Q

When tryptophan is absent

A

The system to produce turns on

24
Q

*A set of two or more adjacent cistrons whose transcription is under the coordinated control of a promoter, an operator, and a regulator gene

A

Operon

25
Q

A segment of DNA that encodes for the formation of a specific polypeptide chain; a structural gene

A

Cistrons

26
Q

*Refers to the process by which genetic information flows from genes to proteins

A

Genetic expression

27
Q

No question

A
28
Q

A specific DNA sequence that directs RNA polymerase to bind to DNA, to open the DNA double helix, and to begin synthesizing an RNA molecule

A

Promoter

29
Q

A short region of regulatory DNA of defined nucleotide sequence that is recognized by a repressor protein

A

Operator

30
Q

*The promoter and operator are arranged so that when the tryptophan repressor occupies the operator

A

It blocks access to the promoter by RNA polymerase, thereby preventing expression of the tryptophan-producing enzymes

31
Q

No question

A
32
Q

No question

A
33
Q

*A group of genes under coordinated control in bacteria

A

Operon

34
Q

The lactose (lac) operon includes (3)

A
  • Three adjacent genes for lactose-utilization enzymes
  • promoter sequence where RNA polymerase binds
  • operator sequence is where a repressor can bind and block RNA polymerase action
35
Q

Regulation of the lac operon (3)

A
  • regulatory gene codes for a repressor protein
  • in the absence of lactose, the repressor binds to the operator and prevents RNA polymerase action
  • lactose inactivates the repressor, so the operator is unblocked
36
Q
  • Active repressor binds to the operator

- inducer (lactose) binds to and inactivates the repressor

A

Inducible operon (lac operon)

37
Q
  • Repressor is initially inactive

- corepressor (tryptophan) binds to the repressor and makes it active

A

Repressible operon (trp operon)

38
Q

*For many operons, activators enhance

A

RNA polymerase binding to the promoter

39
Q

No question

A
40
Q

No question

A
41
Q

Required for the bacterial RNA polymerase to recognize a promoter

A

Sigma subunit

42
Q

Permits one large set of genes to be turned off and a new set to be turned on simply by replacing

A

One sigma subunit with another

43
Q

In the figure, which one of the two strands of the double helix acts as a template strand for the synthesis of an RNA molecule

A

Strand 2

44
Q

In prokaryotes, a detachable unit called ____ associates with the core enzyme and assists it in reading the signals in the DNA that tell it when to begin transcribing

A

Sigma factor

45
Q

A type of RNA functions in a variety of nuclear processes, including the splicing of pre-mRNA

A

Small nuclear RNA (snRNA)

46
Q

The stage of transcription where RNA nucleotides are added to the chain

A

Elongation

47
Q

For most bacterial genes a termination signal consists of a ____ nucleotide pairs preceded by a two-fold symmetric DNA sequence

A

String of A-T

48
Q

rRNA contains the catalytic activity that joins amino acids together (T/F)

A

True

49
Q

A state called a _____ is the starting point for a relatively slow process in which many side-chain adjustments occur that eventually form the correct tertiary structure of protein

A

Molten globule

50
Q

The lac operon of E. coli is ____ when the repressor is bound to lactose

A

Active

51
Q

Ribosomes are solely made of rRNA (T/F)

A

False

BIO 220 (5 decks)

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