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BIO105 - Genetics > Chapter 5c - Regulation of Gene Expression > Flashcards

Chapter 5c - Regulation of Gene Expression Flashcards

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Biology 101 flashcards
1
Q

virtually every cell in your body contains a __ __ of genes

A

complete set

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2
Q

genes are not all __ __ in every tissue

A

turned on

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3
Q

each cell in the body expresses only how many genes at any time

A

small subset

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4
Q

during development, what do different cells express

A

different set of genes in precisely regulated fashion

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5
Q

where does gene regulation primarily occur

A

transcription

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6
Q

a given cell transcribes only a __ __ of genes and not others

A

specific set

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7
Q

Gene products should be released at the ….

A

right time, right place, right amounts

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8
Q

Gene regulation in prokaryotes are mainly for

A
  1. growth
  2. response to environment
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9
Q
  • cluster of genes that are transcribed together to give a single messenger RNA (mRNA) molecule, which therefore encodes multiple proteins
  • cluster of genes encoding related enzymes that are regulated together
A

operon

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10
Q

who coined the term operon

A
  1. Francis Jacob
  2. Jacques Monod
    1961
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11
Q

where do operons mostly occur

A

prokaryotes

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12
Q

Two Categories of Gene Control

A
  1. Negative regulation
  2. Positive regulation
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13
Q
  • an inhibitor (repressor) is present in the cell that keeps transcription turned off
  • an anti-inhibitor (inducer) is needed to turn the system on
A

negative regulation

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14
Q

inhibitor

A

repressor

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15
Q

anti-inhibitor

A

inducer

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16
Q

an effector molecule which may be a protein, small molecule or a molecular complex activates a promoter

A

positive regulation

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17
Q

Two types of Proteins in Bacterial Cells

A
  1. Structural proteins
  2. Regulatory proteins
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18
Q

do not regulate transcriptio

A

structural proteins

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19
Q

ex. of structural proteins

A
  1. enzymes
  2. membrane proteins
  3. ribosomal components
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20
Q

help sense environment and regulate rate of transcription of structural genes by binding to DNA

A

regulatory proteins

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21
Q
  • contains genes involved in lactose metabolism
  • It’s expressed only when lactose is present and glucose is absent
A

lactose (lac) operon

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22
Q

parts of the lac operon

A
  • P (promoter)
  • O (operator)
  • Z
  • Y
  • A
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23
Q

structural loci of lac operon

A
  • Z
  • Y
  • A
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24
Q

Z is the structural gene for what?

A

beta-galactosidase

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25
Q

Y is the structural gene for what?

A

beta-galactosidase permease

26
Q

A is the structural gene for what?

A

beta-galactosidase transacetylase

27
Q

lactose is absent, __ __, __ __

A
  • repressor active
  • operon off
28
Q

lactose present, __ __, __ __

A
  • repressor inactive
  • operon on
29
Q

what type of promoter is lac operon

A

weak

30
Q

expression level of lac operon

A

basal

31
Q

binding site of lac operon

A

-60 region

32
Q

name of binding site of lac operon

A

CRP (cAMP receptor protein) site

33
Q

CRP

A

cAMP receptor protein

34
Q

effect of cAMP-CRP on gene expression

A

enhancing effect

35
Q

cAMP

A

cyclic adenosine monophosphate

36
Q

what are the operons repressed in the presence of glucose

A
  • maltose
  • sorbitol
  • lactose
  • arabinose
  • galactose
37
Q

what is needed to turn on the sugar-metabolizing operons

A

cAMP

38
Q

when glucose levels are low, __ is produced. It attaches to __, allowing it to bind DNA. Then it helps ____ bind to the promotor, resulting in high levels of transcription

A
  • cAMP
  • CRP
  • RNA polymerase
39
Q

in low glucose, what is the rate of transcription

A

high

40
Q

when glucose levels are high, __ __ is made. __ can’t bind to DNA without it, so transcription occurs only at a low level

A
  • no cAMP
  • CRP
41
Q

in high glucose, what is the rate of transcription

A

low

42
Q

cAMP formation

A

ATP –> (adenylyl cyclase) cAMP + Ppi

43
Q

how does glucose reduce levels of cAMP

A

inactivating adenylate cyclase

44
Q

one of the constitutive genes expressed at the basal level

A

tryptophan (trp) operon

45
Q

gene that is transcribed continually

A

constitutive gene

46
Q

what does the trp operon produce

A

polypeptides that make up enzymes of tryptophan synthesis

47
Q

tryptophan absent, __ __, __ __

A
  • repressor inactive
  • operon on
48
Q

tryptophan present, __ __, __ __

A
  • repressor active
  • operon off
49
Q

eukaryotic gene regulation

A

epigenetic mechanisms

50
Q

highly condensed, gene-poor, and transcriptionally silent

A

Heterochromatin

51
Q

less condensed, gene-rich, and more easily transcribed

A

Euchromatin

52
Q

regions with high transcriptional activity are loosely packed

A

acetylation

53
Q

regions with low or no transcriptional activity are densely packed

A

methylation

54
Q

What are the Epigenetic Mechanisms

A
  1. acetylation
  2. methylation
55
Q

transcriptional activation

A

histone acetylation

56
Q

gene silencing

A

histone deacetylation

57
Q

DNA coiled = ?

A

turned OFF

58
Q

what does acetylation unfold

A

chromatin

59
Q

histones that unfold chromatins

A

H3 and H4 histones

60
Q

favors condensation and leads to inactive DNA once CH3 is passed generationally

A

methylation of nucleotides

BIO105 - Genetics (19 decks)

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