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BIO 190: UNIT 3 > Chapter 12: The Control of Genetic Information via Gene Regulation > Flashcards

Chapter 12: The Control of Genetic Information via Gene Regulation Flashcards

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1
Q

Define gene regulation.

12.1

A

The ability of cells to control the expression of their genes.

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2
Q

What is gene expression?

12.1

A

the process by which the information within a gene is made into a functional product, such as an RNA molecule or a protein

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3
Q

Define constitutive genes.

12.1

A

unregulated gene that has constant levels of expression in all conditions over time

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4
Q

How do living organisms benefit from gene regulation?

12.1

A
  1. conserves energy by producing only what is needed
  2. ensures that genes are expressed in the appropriate cell types & at correct stage of development (in multicellular organisms)
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5
Q

How do proteins regulate gene expression?

12.1

A

through binding to DNA

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6
Q

The different cell types of an individual contain the same ________, meaning they carry the same set of genes. However, their _______, which is the collection of proteins they make, is quite different.

12.1

A

genome; proteome

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7
Q

How does gene regulation play a role in mammals (embryonic and fetus stages)?

12.1

A

gene regulation plays a role in ensuring that an embryo and fetus get a proper amount of oxygen; offspring can take oxygen from the maternal bloodstream

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8
Q

T or F: During mammalian development, all globin genes are expressed during all developmental stages.

12.1

A

False; DIFFERENT globin genes are expressed at DIFFERENT developmental stages

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9
Q

Which process is present in the gene expression of Eukaryotes that Prokaryotes lack?

12.1

A

RNA modification

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10
Q

Gene regulation most commonly occurs at the level of ____________.

12.1

A

transcription

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11
Q

There are 5 different types of gene expression during the developmental stages of a mammal. Determine which ones occur during the embryonic stage, fetal stage, and birth to adult stage.

12.1

A

Embryonic: epsilon and zeta globin genes
Fetal: alpha and gamma globin genes
Birth: alpha and beta globin genes

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12
Q

Define regulatory transcription factors.

12.2

A

proteins that bind to regulatory sequences in the DNA, usually in the vicinity of a promoter and either increase of decrease the rate of transcription of a gene

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13
Q

What type regulatory transcription factors decrease the rate of transcription, and what is this form of regulation called?

12.2

A

repressors; negative control

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14
Q

Try your best to draw what a negative control looks like on a whiteboard or piece of paper! :)

12.2

A
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15
Q

Try your best to draw what a positive control looks like on the whiteboard or a piece of paper! :)

12.2

A
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16
Q

What is the function of a small effector molecule?

12.2

A

they bind repressors or activators, causing a change in their conformation and function

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17
Q

What is an operon? Where can they be found?

12.2

A

a cluster of genes ( 2+ ) that is under the transcriptional control of one promoter; found in bacterial chromosomes

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18
Q

Define the functions of each step in Eukaryotic gene expression (i.e., transcription, RNA modification, translation & post-translation).

12.1

A

Transcription: control of synthesis of mRNA from a gene
RNA modification: regulation of splicing of mRNA
Translation: regulation of protein synthesis
Post-translation: regulation of the amount or function of a protein that has already been synthesized

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19
Q

What is the advantage of operon organization in bacteria?

12.2

A

bacteria can coordinate the expression of multiple genes in the same biological pathway

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20
Q

What are the basic components of the lac operon (lactose operon)?

12.2

A

promoter (lacP), and three structural genes: lacZ, lacY, and lacA

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21
Q

In the lac operon, the ______ is the DNA sequence at which the lac repressor binds.

12.2

A

operator (lacO site)

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22
Q

What is the CAP site for the lac operon?

12.2

A

a regulatory sequence in the DNA that is recognized by an activator protein

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23
Q

How does the presence of lactose in the cell influence the transcription of the lac operon?

12.2

A
  1. when lactose is present, transcription of the lac operon is high
  2. when lactose is present, the lac repressor protein does not bind to the operator site and transcription can occur
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24
Q

How does allolactose affect the lac repressor protein?

12.2

A

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

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25
Q

The catabolite activator protein (CAP) is involved in ______ control of the lac operon.

12.2

A

positive

26
Q

Describe the relationship between the level of cAMP and glucose.

12.2

A

glucose present ——-> low cAMP
glucose absent ———> high cAMP

27
Q

Describe the function of glucose and lactose in the lac operon.

12.2

A

glucose BLOCKS activation of the lac operon; lactose RELIEVES repression of the lac operon

28
Q

Which relationship between glucose and lactose allows for the transcription rate of the lac operon to be very high? Why?

12.2

A

When lactose is HIGH and glucose is LOW, the rate is very high because CAP is bound to the CAP site and lac repressor is not bound to the operator; bacteria readily metabolize lactose

29
Q

Which factors help increase transcription levels in eukaryotes?

12.3

A
  1. binding of an activator protein to DNA
  2. loosening of chromatin structure
30
Q

How does eukaryotic regulation differ from prokaryotic?

12.3

A
  1. genes are organized individually (not in operons)
  2. tends to be more intricate bc they possess complexities not found in prokaryotes
31
Q

What factors INHIBIT transcription in eukaryotes?

12.3

A
  1. repressors inhibit RNA polymerase to initiate transcription
  2. DNA methylation inhibits transcription by preventing binding of activator OR by recruiting proteins that inhibit transcription
32
Q

The lac operon is turned off/on in the presence of lactose.

12.2

A

on

33
Q

How does the cell recognize that lactose needs to be metabolized?

12.2

A

lactose is converted into allolactose, which inhibits the lac repressor

34
Q

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

12.2

A

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

35
Q

What are the two components of the core promoter in eukaryotes?

12.3

A

TATA box and transcriptional start site

36
Q

Under what conditions does the lac repressor bind to the operator of the lac operon and prevent transcription?

12.2

A

when the concentration of lactose is LOW in the cell

37
Q

How does allolactose affect the lac repressor protein?

12.2

A

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

38
Q

What determines the precise starting point for transcription?

12.3

A

the TATA box

39
Q

What are enhancers? What about silencers?

12.3

A

Enhancers: DNA sequences that increase transcription
Silencers: DNA sequences that prevent transcription

40
Q

Bacteria requires once transcription factor (called sigma factor) to initiate transcription. How many do eukaryotes need? What are they called?

12.3

A

RNA polymerase II requires 5 different proteins called general transcription factors (GTFs) in eukaryotes

41
Q

What is the function of general transcription factors (GTFs) in the initiation of transcription?

12.3

A

GTFs and RNA polymerase come together at the core promoter for the initiation of transcription

42
Q

A sequence upstream of the transcriptional start site. Determines the precise starting point for transcription. These factors describe what?

12.3

A

the TATA box

43
Q

Try to draw an illustration of how an activator can regulate the function of RNA polymerase by affecting the function of GTFs. Make sure to include the following: activator, coactivator, enhancer, TATA box, TFIID, and the pre-initiation complex! :)

12.3

A
44
Q

Identify the two ways that a repressor can interact with a GTF to inhibit transcription.

12.3

A
  1. a repressor can prevent binding of TFIID to the TATA box
  2. a repressor can inhibit assembly of the pre-initiation complex
45
Q

Suppose a mutation in the lacl gene prevented lac repressor from being made. How would this mutation affect the expression of the lac operon?

12.2

A

it would be expressed in the presence or absence of lactose in the environment

46
Q

What serves as a target for activators or repressors to either promote or inhibit translation?

12.3

A

TFIID (transcription factor IID)

47
Q

Depending on the locations and arrangements of ___________, regions of DNA may or may not be accessible for transcription.

12.4

A

nucleosomes

48
Q

What is the difference between a region in a closed and open conformation?

12.4

A

Closed: transcription is difficult/impossible
Open: accessible to GTFs and RNA polymerase, thus, can be transcribed

49
Q

What are the 3 different ways that chromatin-remodeling complexes can change chromatic structure?

12.4

A
  1. binding to a chromatic and changing the positions of nucleosomes
  2. removing histones from DNA
  3. replacing standard histones with histone variants
50
Q

T or F: Acetylated histone proteins do not bind as tightly to the DNA, which promotes transcription.

A

true

51
Q

Many eukaryotic genes are flanked by a nucleosome- ______ ________, which is a site that is missing nucleosomes.

12.4

A

free region

52
Q

Briefly describe the sequence that occurs during the recruitment of chromatin-remodeling complexes and histone-modifying enzymes to the promoter region.

12.4

A
  1. activator binds to an enhancer in the nucleosome-free region (NFR)
  2. activator recruits chromatin-remodeling complex and histone modifying enzymes
  3. biding of GTFs and RNA polymerase II to the core promoter is facilitated; preinitiation complex forms
  4. histones are evicted/shifted from promoter region, or destabilized so RNA polymerase II can pass
  5. transcription occurs
53
Q

DNA _______ usually inhibits the transcription of eukaryotic genes, particularly when it occurs in the vicinity of the __________.

12.4

A

methylation; promoter

54
Q

How does methylation inhibit transcription?

12.4

A

by preventing the binding of an activator OR by facilitating the binding of proteins that inhibit transcription

55
Q

The formation of what, is a way to silence genes in a tissue specific manner?

12.4

A

facultative heterochromatin

56
Q

When a pre-mRNA has multiple introns and exons, the coding sequences can be put together in more than one way. This process, which results in the production of two or more different polypeptides, is termed __________ ____________.

12.5

A

alternative splicing

57
Q

When iron levels are low, the iron regulatory protein:

12.5

A

binds to the iron regulatory element (IRE) and blocks translation of ferritin

58
Q

The mRNA encoding ferritin is controlled by an RNA-binding protein called the _______.

12.5

A

iron regulatory protein

59
Q

Another way to regulate mRNAs involves _______________, that directly affect the initiation of translation.

12.5

A

RNA-binding proteins

60
Q

T or F: Alternative splicing of pre-mRNAs decreases protein diversity.

12.5

A

false; it INCREASES protein diversity

61
Q

When the iron regulatory protein (IRP) is bound to ______, translation is blocked. When the IRP is bound to _____, translation proceeds.

12.5

A

IRE; iron

BIO 190: UNIT 3 (7 decks)

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