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BIOL 2030 > Section 2 - Module 9 > Flashcards

Section 2 - Module 9 Flashcards

1
Q

What is an operon?

A

a group of bacterial structural genes, under the control of a single promoter, they are transcribed together, produce a single mRNA molecules that encodes different proteins, and regulates the expression of genes by controlling transcription

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2
Q

PROG

A

Promoter regulator operator gene

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3
Q

T/F. Operons can be induced or repressed?

A

True

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4
Q

Is the regular gene considered apart of the operon?

A

No, but is does affect operon function

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5
Q

What binds to the operator site to regulate the transcription of mRNA?

A

Regulator protein

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6
Q

What is the effect on transcription of the operon when the regulator protein binds to the operon DNA?

A

Either positive of negative control

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7
Q

Negative control

A

regulatory protein is a repressor, binding to DNA and inhibiting transcription

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8
Q

Positive control

A

regulatory protein is an activator, biding to DNA and stimulating transcription

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9
Q

What is the regulatory molecule?

A

a metabolite (precursor or product of metabolic pathway)

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10
Q

What binds the regulatory protein to affect transcription of the operon?

A

Regulatory molecule

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11
Q

Inducible operon

A

transcription is normally OFF (not taking place). When the regulatory molecules binds to the regulatory protein transcription if turned ON.

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12
Q

Repressible operon

A

transcription is normally ON (taking place). When regulatory molecules binds to regulatory protein transcription is turned OFF.

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13
Q

What is an allosteric site?

A

effector binding sites within enzymes, distinct from the active site of the enzyme.

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14
Q

Negative inducible operons

A

regulate the synthesis of the enzyme economically: they are synthesized only when their substrate is available

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15
Q

Negative repressible operons

A

can use the product (U) to provide negative feedback…turning off the genes involved in synthesis

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16
Q

What is the lac operon of E.coli an example of?

A

Negative inducible feedback

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17
Q

What enzymes are involved in lactose metabolism?

A

permease and beta-galactosidase

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18
Q

Function of permease

A

actively transports lactose into the cell

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19
Q

Function of beta-galactosidase

A

break lactose into galactose and glucose. Also converts lactose into the related compound allolactose, and converts allolactose galactose and glucose. ( so both direct and indirection products)

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20
Q

How many carbons is lactose made up of?

A

six

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21
Q

What enzymes are encoded by adjacent structural genes in the lac operon and have a common promoter (lacP)?

A

beta-galactosidase, permease, and transacetylase

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22
Q

What gene is associated with beta-galactosidase?

A

lac Z

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23
Q

What gene is associated with permease?

A

lac Y

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24
Q

what gene is associated with transacetylase?

A

lac A

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25
Q

Lac operon positive/negative? inducible/repressible?

A

negative inducible

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26
Q

Cis acting

A

able to control the expression of genes on the same piece of DNA

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27
Q

trans acting

A

able to control the expression of genes on other DNA molecules

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28
Q

How can the plasmid replicate?

A

independently

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29
Q

What is a plasmid?

A

a small DNA molecule within a cell that is physically separated from a chromosomal DNA

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30
Q

Lac mutations

A

structural-gene mutation, regulator-gene mutation, operator mutation, promoter mutation

31
Q

What type of genes are Lac Z, Y and A?

A

structural genes

32
Q

What type of gene is Lac I?

A

regulator gene

33
Q

What type of gene is Lac O?

A

operator

34
Q

What does mutation LacZ and LacY structural genes affect?

A

Alter the amino acids and affect the structure of the proteins.

35
Q

In structural gene mutations is beta-galactosidase and permease still produced?

A

Yes, because of the presence of lactose

36
Q

What does structural-gene mutations effect?

A

only the product of the gene in which the mutation occurred

37
Q

What dominance it lac I?

A

trans dominant, so only produces beta-galactosidase in the presence of lactose

38
Q

Effect of lactose with regulator-gene mutations and beta-galactosidase?

A

Because Lac I is trans dominant, it can bind to both activator and repress transcription in the absence of lactose. When lactose is present, it inactivates the repressor, and functional beta-galactosidase is produced from the lac Z gene.

39
Q

Regulator-gene mutations effect

A

the partial diploid fails to produce beta-galactosidase in the presence and absence of lactose because the lac I gene encodes a super repressor.

40
Q

Operator mutations (Lac O)

A

constitutive and cis acting (no lactose it will bind) (with lactose no active repressor binding and beta-galactosidase transcribed and translated)

40
Q

What sugar does E.coli metabolize preferentially?

A

Glucose, because glucose enters glycolysis without further modifications therefore requiring less energy to metabolize than other sugars do

40
Q

Catabolic repression

A

genes that participate in the metabolism of sugars turn off when glucose is available

40
Q

Promoter mutations

A

don’t produce lac proteins either in the presence or in the absence of lactose.

41
Q

lac operon positive/negative by _

A

CAP

42
Q

lac operon inducible/repressible by _

A

cAMP

43
Q

CAP

A

catabolite activator protein

44
Q

When glucose is high was happens with CAP/cAMP?

A

cAMP is less likely to bind to CAP (results in little transcription)

45
Q

When glucose is high was happens with CAP/cAMP?

A

cAMP binds to CAP (forms complex)

46
Q

What does CAP and cAMP complex cause?

A

increases the efficiency of polymerase binding, then when lactose is present is results in high rates of transcription and translation of the structural genes and the production of glucose and lactose.

47
Q

What are the levels that gene expression can be controlled on?

A

1) alternation of DNA or chromatin structure
2) transcriptional control
3) RNA processing and degradation
4) translational control
5) post-translational modification

48
Q

Types of alternation of DNA or Chromatin structure

A

1) Chromatin remodeling
2) histone modification and DNA methylation

49
Q

Types of transcriptional control

A

1) transcriptional factors and regulation proteins
2) enhancers and insulators

50
Q

Types of RNA processing and degradation

A

1) RNA splicing and multiple 3’ cleavage sites
2) RNA interference (siRNA, miRNA, and methylation)

51
Q

Types of translational control

A

1) miRNA regulation of translation
2) availability of components for translation

52
Q

Types of post-translational modifications

A

1) protein modification and degradation

53
Q

Chromatin remodeling

A

Chromatin-remodeling complexes bind directly to particular sites on DNA and reposition the nucleosomes, allowing other transcription factors and RNA polymerase to bind to
promoters and initiate transcription

54
Q

Histone modification and DNA methylation

A

a) methylation of histones and DNA: addition of methyl groups to the tails of histone proteins and/or DNA brings about either the activation or the repression of transcription
b) acetylation of histones: addition of acetyl groups (CH3CO) to histones usually stimulates transcription

55
Q

Transcriptional factors and regulator proteins

A

transcriptional activator proteins stimulate and stabilize the basal transcription apparatus. They interact directly or indirectly though coactivator proteins

56
Q

Enhancers

A

regulatory elements that affect the transcription of distant genes. They can stimulate any promoter in their vicinity .

57
Q

Insulators

A

block the effect of enhancers in a position dependent manner.

58
Q

When does the insulator block the action of an enhancer on a pormoter?

A

When the insulator lies between the enhancer and the promoter

59
Q

Alternative splicing

A

allows pre-mRNA to be spliced in multiple ways, generating different proteins in different tissues or at different times in development.

60
Q

Multiple 3’ cleavage sites

A

use different cleavage sites to produce mRNA’s of different length

61
Q

What exon for drosophila carries a stop codon?

A

Exon B

62
Q

What does RNA silencing lead to?

A

degradation of mRNA or to the inhibition of translation or transcription

63
Q

How do siRNA degrade mRNA?

A

cleavage

64
Q

What does miRNAs lead to?

A

inhibition and/or mRNA degradation

65
Q

how do come siRNAs bring about inhibiting transcription?

A

by bringing about methylation of histone proteins or DNA

66
Q

miRNA regulation of translation

A

miRNAs inhibit the translation of complementary mRNAs. Researchers suggest that miRNA can inhibit the initiation step of translation as well as steps after initiation, such as ribosome stalling or premature termination.

67
Q

What causes an increase in availability of initiation factors foo translation?

A

virus exposure

68
Q

What increases the rate of translation and protein and protein synthesis increase?

A

virus exposure

69
Q

Availability of components for translation

A

Ribosomes, charged tRNAs, initiation factors, and elongation factors are all required for the translation of mRNA molecules. The availability of these components affects the rate of translation and therefore influences gene expression.

70
Q

Protein modification and degradation

A

selective cleavage and trimming of amino acids from the ends, by acetylation, or by the addition of phosphate groups, carboxyl groups, methyl groups, carbohydrates, or ubiquitin (a small protein).

BIOL 2030 (7 decks)

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