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BIO 1A03 > T3- M1&2 > Flashcards

T3- M1&2 Flashcards

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Biology 101 flashcards
1
Q

What type of environment does prokaryotic growth need

A

A nutrient rich environment containing amino acids and carbs

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2
Q

Describe housekeeping genes

A

Their DNA has genes always required for function

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3
Q

What are housekeeping genes required for

A

General maintenance

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4
Q

What do housekeeping genes include

A
  • structural proteins
  • ribosomal proteins
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5
Q

Define regulated genes

A

Genes that can be turned on/off on demand
- expressed only when needed

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6
Q

Are enzymes housekeeping or regulated genes

A

Regulated

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7
Q

Why must cells metabolize energy

A

For ATP and other energy sources

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8
Q

What is the preferred energy source in E coli

A

Glucose

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9
Q

What happens once glucose is used up in bacteria

A

Growth is stopped

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10
Q

What do bacteria metabolize when glucose runs out

A

Lactose

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11
Q

What activates the switch to lactose

A

Products of glucose metabolism

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12
Q

Why aren’t lactose enzymes before glucose runs out

A

It would be a waste without lactose

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13
Q

What happens if lactose is present without glucose

A

Bacteria can quickly uptake lactose metabolizing genes to accommodate for new environment

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14
Q

What enzyme is needed to metabolize lactose

A

Beta galactosidase

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15
Q

What does lactose break down into

A

Glucose and galactose

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16
Q

Can beta galactosidase be made with glucose in cell

A

No

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17
Q

What did Jacob and Monod do

A

Grew E coli in lactose free medium, added it and removed to see if protein production changed

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18
Q

What pattern did Jacob and Monod see

A

There was a steady increase in response to more lactose

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19
Q

What did Jacob and Monod conclude

A

Figured out how bacteria controlled the production of an enzyme called beta-galactosidase

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20
Q

Does gene expression mean transcription?

A

No

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21
Q

Define gene expression

A

Functional product of gene is made, modified and activated

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22
Q

What does transcriptional control allow

A

transcription of DNA to mRNA

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23
Q

What does translational control allow

A

Translation of mRNA to protein

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24
Q

What does post translational control allow

A

Modification and activation of produced protein

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25
Q

What does transcriptional regulation control

A

Amount of mRNA produced

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26
Q

What does activation of transcription require

A

Binding to promoter and increase binding of RNA Polymerase

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27
Q

How is the gene turned off and on

A

Controlled binding of protein to promotor

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28
Q

Rank transcriptional regulation from slowest to fastest and why

A

Slowest- starting from scratch!
- relevant with drastic changes

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29
Q

What is an example of transcriptional regulation

A

When cell runs out of glucose and lactose metabolism is needed

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30
Q

Is transcriptional regulation efficient?

A

Yes! It does not use resources unless necessary

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31
Q

How is translation initiated in eukaryotes?

A

Binding of ribosome to 5’ cap and first AUG start codon

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32
Q

How is translation initiated in prokaryotes?

A

Ribosome binds and begins translation at Shine Dalgarno sequences

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33
Q

What does the rate of translation effect

A

Amount of protein produced

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34
Q

What does protein production depend on

A

Stability of mRNA

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35
Q

What does post translational control allow the polypeptide to do

A

Fold and be further chemically modified

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36
Q

How does post translational control effect protein activation

A

Cause proteins to be active/inactive by driving it into complexes, substrate binding, unmasking enzymatic domains

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37
Q

Rank post translational control from slowest to fastest

A

Fastest

38
Q

How does post trans control respond to changes

A

Quick

39
Q

Define enhancers

A

Short region of DNA that can be bound by proteins to increase the likelihood that transcription of a particular gene will occur

40
Q

At what level does E coli regulate beta galactosidase

A

Transcriptional level

41
Q

When is there activation in gene expression for beta galactosidase and lactose permease

A

When there is no glucose present in cell

42
Q

What is lactose permease

A

A transport protein

43
Q

Where does lactose permease sit

A

In the bacterial cell membrane

44
Q

What does lactose permease do

A

Allows transport of lactose into cell

45
Q

What is beta galactosidase

A

Cytoplasmically situated bacterial enzyme

46
Q

What does beta galactosidase do

A

Cleaves imported lactose into glucose and galactose

47
Q

Why are lactose permease and beta galactosidase linked

A

Because of functional relatedness

48
Q

What does clustering genes with one operon do

A

Allow ability to control transcription of whole gene cluster as one unit

49
Q

Who discovered the operon model

A

Francois Jacob and Jacques Monod in 1961

50
Q

What does the operon model describe

A

Functionally related bacterial genes are organized into transcriptional units along bacterial chromosome

51
Q

What controls the on and off of a gene

A

The operon

52
Q

What does the operon consist of

A

The promoter, operator, and coordinated gene cluster whose products function in similar way

53
Q

What is an operator

A

A sequence of nucleotides at beginning of operon that can be regulated to inhibit or allow transcription

54
Q

What happens when operator is not bound to inhibitor

A

RNA polymerase can bind to operator and transcribe genes in protein

55
Q

Why can bacteria produce separate polypeptides during translation

A

Because the polycistronic mRNA is punctuated with stop and start codons

56
Q

What is the lac operon

A

Model for transcriptional regulation in prokaryotes such as E coli

57
Q

What is under control in lac operon

A

Beta galactosidase and lactose permease expression

58
Q

What regulatory sequences exist in lac operon

A

Promotor- binds RNA polymerase
Operator (lac O)- binding site for repressor protein expressed by lacI

59
Q

What are the two main structural genes that code for lactose metabolism

A

lacY and lacZ gene

60
Q

What does the lacY gene do

A

Codes for lactose permease which will be embedded in the cell membrane

61
Q

What does the lacZ gene do

A

codes for beta galactosidase which cleaves lactose into glucose and galactose

62
Q

What does lacI do

A

Controls expression of lacZ and lacY gene

63
Q

How does lacI control expression

A

Codes for repressor proteins which binds to operator and inhibits transcription

64
Q

What does the repressor protein do to stop transcription

A

Binds to operator region of operon so RNA polymerase cannot bind

65
Q

When is the repressor protein expressed

A

During low levels of lactose

66
Q

Define negative transcriptional regulation

A

Ability of repressor protein to inhibit transcription

67
Q

How is expression of repressor protein when there are high levels of lactose

A

High expression to inhibit

68
Q

Describe the structure of the repressor protein

A

Tetrameric protein

69
Q

How does repressor protein inhibit

A

Binds to lacO so RNA cannot bind

70
Q

How does lactose act as inducer

A

Binding to repressor protein on lac operon and causing change to repressor- so it cant bind with DNA

71
Q

What happens when operator is not bound by repressor

A

RNA polymerase can bind and produce b galactosidase and lactose permease

72
Q

What type of feedback is regulation of lac operon

A

Positive regulation

73
Q

What increases as glucose levels decrease

A

Intracellular cyclic AMP

74
Q

What does intracellular cAMP do

A

Increase of cAMP contributing to positive regulation of lac operon

75
Q

What is a good indicator of nutritional state of E coli cells

A

Concentration of cAMP

76
Q

Define adenylyl cyclase

A

Catalyzes the production of cAMP from ATP

77
Q

How is adenylyl cyclase effected when glucose levels are high

A

It is inhibited

78
Q

How are cAMP levels when glucose is low

A

High due to increased activity of adenylyl cyclase

79
Q

How are cAMP levels when glucose is high

A

Low due to decreased activity of adenylyl cyclase

80
Q

What protein does positive regulation of lac operon include

A

CRP (cyclic AMP Receptor Protein) or CAP (Catabolite Activator Protein)

81
Q

What does CAP do

A

protein that binds to the promoters of operons that control the processing of alternative sugars, such as the lac operon

82
Q

What happens when CAP bound by cAMP

A

It will bind to different site on bacterial DNA called CRP-cAMP or CAP-cAMP

83
Q

How does cAMP respond to elevated signals

A

cAMP binds to CRP protein as allosteric activator

84
Q

What happens when CRP-cAMP complex binds to bacterial DNA

A

Activate transcription of beta galactosidase and lactose permease in presence of lactose

85
Q

What do low levels of glucose do to cAMP

A

Increase cAMP levels to activate positive regulator CRP-cAMP

86
Q

What happens to repressor in negatively regulated transcription

A

A repressor will bind to operon to prevent polymerase from binding

87
Q

Inducer proteins become..?

A

Inducer of genes

88
Q

What happens to activator protein in positive regulation and why?

A

Binds to activator binding site on DNA
- allows for recruitment of RNA polymerase to promotor and initiation of transcription

89
Q

What happens if activator is absent or cannot bind?

A

Transcription cannot occur

90
Q

How is lac operon regulated in low glucose

A

Positively regulated

91
Q

How is lac operon regulated in high glucose

A

Negatively regulated

BIO 1A03 (10 decks)

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