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Biol 207 > Topic 7-3 > Flashcards

Topic 7-3 Flashcards

1
Q

the process by which a gene creates a “gene product” (ex: proteins, RNA) that have cellular/organismal functions

A

gene expression

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2
Q

mechanisms that have evolved to control gene expression, controlling the flow of information

A

gene regulation

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3
Q

provides the molecular basis for the relationship between genotype and phenotype

A

gene expression

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4
Q

encoding products that interact with other sequences and affect the transcription and translation of these sequences

A

regulatory genes

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5
Q

DNA sequences that are not transcribed but play a role in regulating other nucleotide sequences

A

regulatory elements

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6
Q

encoding proteins

A

structural genes

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7
Q

continuously expressed under normal cellular conditions

A

constitutive expression

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8
Q

in bacteria, gene regulation maintains internal ________, turning genes on and off in response to _________.

A

flexibility, environmental changes

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9
Q

in multicellular eukaryotic organisms, gene regulation also brings about __________.

A

cell differentiation

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10
Q

transcription in bacterial cells is regulated by:

A

operons

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11
Q

is composed of a promoter + additional sequences that control transcription (operator) + structural genes

A

operon

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12
Q

a DNA sequence which encodes products that affect the operon function but are not part of the operon

A

regulator gene

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13
Q

inducible and repressible operons

A

negative and positive controls

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14
Q

list two examples of operons in E.coli

A
  • the lac operon
  • the trp operon
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15
Q

used classical genetics to uncover the”operon model” of how bacteria regulate genes

A

Francois Jacob and Jacques Monod

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16
Q

operons allow the cell to coordinate:

A

expression of multiple gene products with one promoter

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17
Q

usually, the structural genes in an operon have:

A

a related function

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18
Q

DNA binding proteins that can bind to DNA in the operon to regulate transcription either negatively (repressors) or positively (activators)

A

regulatory proteins

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19
Q

repressors bind operators and blocks RNA pol. and transcription

A

negative control

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20
Q

activator ususally do not bind operators, and frequently bind to promoters and facilitate RNA pol. binding and transcription

A

positive control

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21
Q

proteins that change shape and function upon binding other proteins

A

allosteric proteins

22
Q

transcription is usually off and needs to be turned on

A

inducible operon

23
Q

transcription is normally on and needs to be turned off

A

repressible operons

24
Q

the control at the operator site is negative. molecule binding is to the operator inhibiting transcription. such operson are usually off and need to be turned on.

A

negative inducible operons

25
Q

a small molecule (allosteric modulator) that turns on transcription

A

inducer

26
Q

the control at the operator site is negative. but such transcription is usually on and needs to be turned off

A

negative repressible operons

27
Q

a small molecule (allosteric modulator) that binds to the repressor and makes it capable of binding to the operator to turn off transcription

A

co-repressor

28
Q
  • the inducer is a precursor for enzymes produced by the operon, thus transcription itself leads to more enzymes and effects levels of inducer
  • feedback system allowsbacteria to adapt to their environment and function more economically
  • some genes are only made if the precursor/inducer is present (less wasteful production of enzymers)
    these are characteristics of:
A

a negative inducible operon

29
Q
  • a negative inducible operon
  • invovled in lactose metabolism
  • inducer: allolactose
    these are characteristics of:
A

the lac operon

30
Q

what is the lac operon repressor encoding gene?

A

lacI

31
Q

what is the lac operon promoter?

A

lacP

32
Q

what is the lac operon operator?

A

lacO

33
Q

what are the encoding beta-galactosidases of the lac operon?

A

lacZ

34
Q

what is the encoding permease of the lac operon?

A

lac Y

35
Q

what is the encoding transacetylase of the lac operon?

A

lacA

36
Q

true or false: the repression of the lac operon completely shuts down transcription

A

false

37
Q

bacterial cells utilize the lac operon to respond to changing ________ levels in the environment by efficiently switching on and off _________.

A

glucose/lactose, lactose metabolism

38
Q

what is the preferred energy source for E.coli?

A

glucose

39
Q

can be used as energy for E.coli if it is broken down via catabolism

A

lactose

40
Q

catabloizes lactose into galactose into glucose, or into allolactose

A

beta galactosidase

41
Q

allolactose acts as an _______

A

inducer

42
Q

an activator protein that binds just upstream of the lac operon promoter and promotes transcription. requires binding to cAMP to bind the DNA

A

catabolite activator protein (CAP)

43
Q

occurs where in a high concentration fo the catabolite, transcription is repressed

A

catabolite repression

44
Q

CAP is an example of ________ of an operon

A

positive control

45
Q

Jacob and Monod used ______ strains of bacteria that contain plasmid F (which would carry a second copy of the lac operon that they could mutatue).with different combinations of mutations in the bacterial genome adn plasmid F, they could determind if mutations had a ________ of ________ effect on lactose metabolism

A

partial-diploid, dominant, recessive

46
Q

a situation where a gene on a separate piece of DNA affects the transcription of another gene.

A

trans-acting factor

47
Q

a situation where one gene will affect the transcription of another gene on the same strand of DNA

A

cis-acting factor

48
Q

lacZ, lacY - mutations affected amounts of beta-galactosidase or permease independently

A

structural mutations

49
Q

mutations in lacI affect both beta-galactosidase and permease levels

A

regulator gene mutations

50
Q

some mutations in lacI resulted in lac proteins being produced all the time regardless of lactose levels. this is called a:

A

constitutive mutant

51
Q

if mutations occured in only one copy of lacI (either plasmid or genome), both lac operons functioned normally. this indicated that the lacI+ gene was:

A
  • dominant over the lacI- gene
  • lacI was a trans-acting factor (encodes regulatory protein)
52
Q

some constitutive mutations of lac proteins were evident only if the structual genes on the same DNA (plasmid or genome) were not mutated. these mutations were found to be in the _______ and prevent the binding of the regulator protein –> thus are ________ elements. overall this is a ________ mutation.

A

lacO operator, cis-regulating, operator gene

Biol 207 (34 decks)

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