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Genetics > Chapter 5c: Regulation of Gene Expression > Flashcards

Chapter 5c: Regulation of Gene Expression Flashcards

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Biology 101 flashcards
1
Q

A given cell transcribes only a specific set of __ and not others (i.e. Insulin is made by pancreatic cells)
* Therefore, gene products should be released at the __ __, in the __ __, and in the __ __

A
  • genes
  • right time
  • right place
  • right amounts
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1
Q

Gene regulation occurs primarily at the level of __ or production of __

A
  • transcription
  • mRNA
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2
Q

What is the primary purpose of gene regulation in prokaryotes? (2)

A
  • growth
  • response to environment
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3
Q

Who proposed the operon model and when?

A

Francis Jacob and Jacques Monod proposed the operon model in 1961.

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4
Q

a cluster of genes encoding related enzymes that are regulated together.

A

operon

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5
Q

Gene control that involves an inhibitor (repressor) that keeps transcription turned off until an anti-inhibitor called inducer turns the system on.

A

Negative regulation

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6
Q

Gene control that involves an effector molecule (protein, small molecule, or molecular complex) that activates a promoter.

A

Positive regulation

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7
Q

Two Categories of Gene Control (2)

A
  • Negative regulation
  • positive regulation
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8
Q

Two Types Of Proteins In Bacterial Cells (2)

A
  • structural proteins
  • regulatory proteins
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9
Q

a protein that do not regulate transcription. Examples include enzymes, membrane proteins, and ribosomal components.

A

structural proteins

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10
Q

Examples of structural proteins (3)

A
  • enzymes
  • membrane proteins
  • ribosomal components.
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11
Q

A protein that helps sense the environment and regulate the rate of transcription of structural genes by binding to DNA.

A

regulatory proteins

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12
Q

In which organism has gene regulation been well studied?

A

E. coli

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13
Q

What does a bacterial cell do when it encounters a potential food source?

A

It manufactures the enzymes necessary to metabolize that food.

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14
Q

Who studied the ability of E. coli to digest lactose and when?

A

Jacques Monod and Francois Jacob studied this in 1959.

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15
Q

What enzyme does E. coli make in the presence of lactose?

A

Beta-galactosidase.

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16
Q

What is the function of beta-galactosidase?

A

breaks down lactose so E. coli can digest it for food.

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17
Q

Which gene in E. coli codes for beta-galactosidase?

A

LAC Z gene

18
Q

Why does E. coli not produce beta-galactosidase in the absence of lactose?

A

no point in making the enzyme if there is no lactose to break down

19
Q

a set of genes in E. coli that are involved in the metabolism of lactose.

A

lactose operon

20
Q

What genes are included in the lactose operon? (3)

A
  • lacZ gene
  • lacY gene
  • lacA gene
21
Q

regulated by a repressor protein that binds to the operator region, preventing transcription when lactose is not present.

A

lactose operon

22
Q

Lactose operon: When __ is present, it binds to the __, causing it to change __ and __ from the operator, allowing transcription of the operon genes.

A
  • lactose
  • repressor
  • shape
  • release
23
Q

The lac operon promoter sequence is __/___, which is a weak promoter with a basal expression level.

A

TTTACA/TATGTT

24
Q

Where is the CRP (cAMP receptor protein) binding site located?

A

-60 region of the lac operon

25
Q

a homodimeric protein with binding ability to DNA and cAMP.

A

CRP (cAMP receptor protein)

26
Q

enhances gene expression by binding to the CRP binding site and promoting transcription initiation at the lac operon promoter.

A

cAMP-CRP

27
Q

the repression of certain sugar-metabolizing operons in favor of glucose utilization.

A

Catabolite repression

28
Q

Which operons are affected by catabolite repression? (5)
What is needed to turn on these operons?

A
  • maltose
  • sorbitol
  • lactose
  • arabinose
  • galactose metabolism
  • cAMP
29
Q

cAMP binds to the __ __ __ (__), forming __-__ __, which then enhance gene expression by binding to specific sites in the promoter regions of the operons.

A
  • cAMP receptor protein (CRP)
  • cAMP-CRP complexes
30
Q

How is cAMP formed: __ __ catalyzes the conversion of ATP to cAMP and pyrophosphate (PPi).

A

Adenylyl cyclase

31
Q

Glucose reduces the level of cAMP by inactivating __ __.

A

adenylyl cyclase

32
Q

__ glucose levels lead to low cAMP levels, resulting in the repression of other operons.

A

High

33
Q

a set of genes in E. coli responsible for synthesizing the amino acid tryptophan.

A

Tryptophan operon

34
Q

Why do E. coli cells need tryptophan?

A

for protein synthesis

35
Q

What happens when E. coli is swimming in tryptophan-rich medium?

A

absorbs tryptophan instead of synthesizing it

36
Q

How many genes are involved in manufacturing tryptophan in E. coli?

A

A cluster of 5 genes

37
Q

The trp operon is constitutively expressed at the __ __, meaning it is always being transcribed at a __ level regardless of the presence of tryptophan.

A
  • basal level
  • low
38
Q

Properties of Acetylated Histones (2)`

A
  • Less positively charged
  • Chromatin is less condensed
39
Q

__ is a chemical modification of histones in genomic DNA that regulates DNA action, often referred to as an epigenetic mechanism.

A

Acetylation

40
Q

Acetylation of histones, particularly lysine residues on __ __ and __, unfolds __, making DNA more accessible for transcription.

A
  • histones H3
  • H4
  • chromatin
41
Q

__ of nucleotides, often on cytosine residues, favors chromatin condensation and leads to inactive DNA, thereby regulating gene expression.

A

Methylation

42
Q

__ patterns can be passed down generationally, influencing gene expression and potentially contributing to inherited traits and diseases.

A

Methylation

Genetics (18 decks)

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