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BIO 110 > Chapter 14 > Flashcards

Chapter 14 Flashcards

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Biology 101 flashcards
1
Q

The collection of all proteins that are expressed in a cell is known as the

A

proteome

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2
Q

The morphologies of different cell types, such as skin cells and nerve cells, is strikingly different. This is due to the fact that the cells

A

express different genes

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3
Q

What is the process by which a cell controls the level of expression of a specific gene or set of genes in a biological pathway?

A

Gene regulation

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4
Q

When a gene is expressed constantly over time in a cell, it is a(n)

A

constitutive gene

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5
Q

Multicellular organisms ensure that most proteins are produced at appropriate times and in appropriate cell types via the regulation of the ______that encode these proteins.

A

genes

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6
Q

The complete set of genes present in a cell is called its

A

Genome

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7
Q

The different cell types of an individual carry the same set of genes, and so contain the same _______.However, the collection of proteins they make, or ______, is quite different.

A

Genome - Proteome

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8
Q

The ability of cells to control the expression of genes is termed gene ____

A

regulation

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9
Q

Which of the following is an example of developmental gene regulation in mammals?

A

Different globin genes are expressed in the embryo, fetus, and adult.

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10
Q

Genes that have relatively constant levels of expression in all conditions over time are said to be _____ genes.

A

constitutive

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11
Q

What are two major benefits of gene regulation?

A

Expression of genes at appropriate times

The conservation of energy

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12
Q

During development in mammals,

A

different globin genes are expressed at different developmental stages

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13
Q

How do the mammalian embryo and fetus acquire oxygen from the mother’s bloodstream?

A

The embryo and fetus remove oxygen from the mother’s blood stream due to the high binding affinity of hemoglobin made during development.

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14
Q

At what levels does gene regulation occur in bacteria?

A

Post-translation

Transcription

Translation

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15
Q

Which of the following are ways of regulating gene expression in BOTH prokaryotes and eukaryotes?

A

Post-translational regulation

Regulation of transcription

Regulation of translation

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16
Q

When geneticists say a gene is “turned on,” they mean that it is _______ into mRNA.

A

transcribed

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17
Q

Eukaryotes, but not bacteria, can regulate gene expression at the level of

A

mRNA processing

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18
Q

Regulation of bacterial gene expression typically involves all of the following mechanisms except

A

regulation of RNA processing

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19
Q

When is a gene “turned off”?

A

When very little or no mRNA is transcribed from the gene

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20
Q

Match each regulated step of eukaryotic gene expression with the appropriate description.
Transcription
RNA processing
Translation
Post-translation

A

Transcription - The amount of RNA synthesized from a gene is regulated.
RNA processing - Two or more different types of mRNA are created from a single gene.
Translation - The amount of protein synthesized from a mRNA is regulated.
Post-translation - Protein function is affected by feedback inhibition, covalent modifications, and degradation.

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21
Q

How does gene regulation differ between prokaryotes and eukaryotes?

A

Eukaryotes process mRNA transcripts in ways that prokaryotes do not.

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22
Q

At what levels does gene regulation occur in eukaryotes?

A

Transcription

Translation

Processing of mRNA

Post-translation

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22
Q
A
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23
Q

What are regulatory transcription factors?

A

Proteins that bind to DNA and affect the transcription of one or more genes

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24
Q

When transcription is regulated by repressor proteins, this is called _____ control

A

negative

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25
Q

What is the role of repressor proteins in the regulation of transcription?

A

They bind to DNA and decrease the rate of transcription.

26
Q

Transcriptional regulation by activator proteins is a type of regulation called
_____ control

A

positive

27
Q

Regulatory transcription factors influence the expression of genes by affecting the rate of transcription. They do so by binding directly to DNA at or near the_____ site

A

promoter

28
Q

Regulatory transcription factors that bind to the DNA and decrease the rate of transcription are called ______. This is a form of regulation called______control. On the other hand, factors that bind to the DNA and increase the rate of transcription are termed_______.These engage in a form of regulation known as ______ control

A
  1. repressor
  2. negative
  3. activator
  4. positive
29
Q

What is the role of small effector molecules in transcriptional control?

A

They bind to transcription regulatory factors and alter how they bind to DNA.

30
Q

What is an operon?

A

A cluster of genes under the transcriptional control of a single promoter

31
Q

Polycistronic mRNA

A

encodes more than one protein

32
Q

What are the basic components of the lac operon?

A

lacZ

Promoter

lacA

lacY

33
Q

Small effector molecules bind to certain proteins and cause conformational changes that influence the ability of these proteins to bind to DNA. Such proteins are called regulatory_____factors

A

transcription

34
Q

Match each protein expressed by the lac operon and its function in the breakdown of lactose.
β-galactosidase
Lactose permease
Galactoside transacetylase

A

β-galactosidase - Break down of lactose into galactose and glucose

Lactose permease - Transport of lactose across the cell membrane

Galactoside transacetylase - Covalent modification of lactose and lactose analogues

35
Q

In the lac operon, the operator is

A

the DNA sequence at which the lac repressor binds

36
Q

What does the lac operon region contain?

A

Promoter, operator, and three structural genes

37
Q

What are the three major functions of the enzymes encoded by the lac operon?

A

The transport of lactose across the cell membrane

The modification of lactose and lactose analogues

The breakdown of lactose

38
Q

Which of the following genes encodes the lac repressor protein?

A

lacI

38
Q

An activator protein recognizes the ___________ of the lac operon.

A

CAP site

39
Q

How does allolactose affect the lac repressor protein?

A

It binds to the repressor protein and prevents it from binding to the operator site of the lac operon.

40
Q

What is an inducer?

A

A small effector molecule that increases the rate of transcription

41
Q

Why is the lac operon considered inducible?

A

When allolactose is produced, this causes the transcription of the lac operon.

42
Q

A conformational change in the lac repressor protein occurs upon binding of the sugar
_______ to it. This change in shape prevents the repressor from binding to the _____- site.

A

allolactose - operator

43
Q

A ______-effect is mediated by a DNA element that binds regulator proteins, whereas a ______-effect is mediated by genes that encode diffusible regulatory proteins.

A

cis; trans

44
Q

A DNA segment that must be adjacent to the gene that it regulates is known as a(n) ____-____ element.

A

cis-acting

45
Q

The small effector molecule that is involved in the positive control of the lac operon is

A

cyclic AMP

46
Q

How do CAP and cAMP increase the transcription of the lac operon?

A

When CAP and cAMP bind to the CAP site, this enhances binding of RNA polymerase to the promoter site.

47
Q

When glucose is present in a bacterial cell, it can act to repress the expression of the lac operon because it is preferentially used compared to other sugars. What form of transcriptional regulation is this?

A

Catabolite repression

48
Q

Of the four possible environments E. coli could encounter with regard to lactose and glucose, which has the highest levels of lac operon transcription?

A

Low glucose and high lactose

49
Q

What is the role of the corepressor in the expression of the trp operon?

A

The corepressor binds to the repressor protein and causes a conformational change, which allows the repressor to bind to the operator site.

49
Q

The genes in the trp operon code for enzymes that make the amino acid

A

tryptophan

50
Q

The binding of the corepressor to the trp repressor results in what?

A

The repressor binds to the operator and prevents transcription.

51
Q

What is a corepressor molecule?

A

A small effector molecule that binds to a repressor protein

52
Q

How do the roles of small effector molecules in the lac and trp operons differ?

A

The trp repressor requires the presence of the small effector molecule to bind to the operator, while the lac repressor does not.

53
Q

What is a repressible operon?

A

An operon that can be inhibited by the presence of a small effector molecule

54
Q

Which of the following factors help to increase transcription levels in eukaryotes?

A

Binding of an activator protein to DNA

Loosening of chromatin structure

55
Q

At the level of transcription, there are several common factors that contribute to combinatorial control. What are they?

A

DNA methylation usually inhibits transcription.

One or more activator proteins may be involved in transcriptional regulation.

One or more repressor proteins may be involved in transcriptional regulation.

56
Q

What are the three features common to most promoters that are needed for the initiation of transcription of protein coding genes in eukaryotes?

A

TATA box

Transcriptional start site

Regulatory elements

57
Q

What is basal transcription?

A

The low level of transcription activated by the core promoter alone

58
Q

Which of the following describe the TATA box? Choose all that apply.

A

The TATA box determines the precise starting point for transcription.

The TATA box is a sequence upstream of the transcriptional start site.

58
Q

What is the role of the TATA box?

A

The TATA box determines the starting point of transcription.

59
Q
A

BIO 110 (6 decks)

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