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Molecular Biology > Gene Regulation: The Operon > Flashcards

Gene Regulation: The Operon Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

the functioning unit of DNA consisting of a cluster of genes under the control of single promoter; several structural genes arranged under a common promoter and regulated by a common operator

A

operon

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2
Q

T/F the regulators of a given operon are not necessarily coded for by that protein

A

T

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3
Q

a nucleotide sequence that enables a gene to be transcribed; recognized by RNA polymerase which then initiates transcription

A

promoter

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4
Q

a segment of DNA to which a repressor binds

A

operator

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5
Q

the genes that are co-regulated by the operon

A

structural genes

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6
Q

a constantly expressed gene which encodes for repressor proteins

A

regulatory gene

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7
Q

proteins that suppress transcription of a gene in response to an external stimulus

A

repressors

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8
Q

proteins that increase transcription of a gene in response to an external stimulus

A

activators

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9
Q

(small molecule) can displace a repressor (protein) from the operator site, resulting in activation of operon

A

inducers

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10
Q

can bind to the repressor to allow its binding to the operator site

A

corepressor

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11
Q

control of an operon is a type of ____________ that enables organisms to regulate the expression of various genes depending on environmental condition

A

gene regulation

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12
Q

when an inducer is present, it binds to the repressor and makes it unable to bind to the operator, which allows for expression of the operon

A

negative inducible operon

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13
Q

What type of operon is the lac operon?

A

negative inducible operon

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14
Q

what is the inducer molecule in the lac operon?

A

allolactose

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15
Q

corepressors are bound by the repressor protein which causes a conformational change to the active site so the activated repressor protein binds to the operator and prevents transcription

A

negative repressible operon

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16
Q

what type of operon is the trp operon

A

negative repressible operon

17
Q

activator proteins are normally unable to bind to the DNA; when an inducer is bound by the activator protein, it undergoes a change in conformation so that it can bind to the DNA and activate transcription

A

positive inducible operon

18
Q

activator proteins are normally bound to the DNA segment; when an inhibitor (corepressor) is bound by the activator, it is prevented from binding the DNA which stops activation and transcription of the system

A

positive repressible operon

19
Q

codes for the enzyme B-galactosidase which breaks B-galactoside into its component sugars

A

lac Z

20
Q

codes for the B-galactoside permease, a membrane-bound protein constituent of the transport system

A

lac Y

21
Q

codes for B-galactoside transacetylase, an enzyme that transfers an acetyl group from Acetyl-CoA to B-galactosides

A

lac A

22
Q

the lac repressor is inactivated by _____________________ where inducer binding changes the properties of the DNA binding site

A

allosteric interaction

23
Q

What are the repressor’s two binding sites?

A

one for the operator DNA and one for the inducer

24
Q

describe the lac operon mechanism involving glucose.

A

glucose is a better energy source than lactose so there’s no need to turn the operon on if glucose is available

25
Q

cAMP-CAP protein complex serves as a ______________ to induce transcription

A

positive regulator

26
Q

when does cAMP begin to accumulate in the cell?

A

when glucose levels drop

27
Q

signaling molecule that is involved in glucose and energy metabolism in E.coli

A

cAMP

28
Q

what happens when cAMP binds to the CAP

A

the complex binds to the promoter region that switch on the genes for processing of alternative energy source

29
Q

what is the trp operon?

A

it has 5 genes that E.coli can use to synthesize tryptophan when it is not available in the environment

30
Q

What happens to the trp operon when tryptophan is absent?

A

the repressor can’t bind to the operator so the operon is active and tryptophan is synthesized

Molecular Biology (8 decks)

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