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Genetics > Regulation of Gene Expression in Bacteria > Flashcards

Regulation of Gene Expression in Bacteria Flashcards

1
Q

Genes that are always active because their function is always needed- “housekeeping genes”

(Ex: genes that encode for glucose metabolism)

A

Constitutive Genes

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2
Q

Gene activity is induced or repressed in response to the needs of the cell or organism

(genes that encode for lactose metabolism)

A

Regulated genes

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3
Q

Genomic unit characterized by a cluster of genes under the control of a common promoter that are transcribed together

A

Operon

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4
Q

Bound by transcriptional repressors to inhibit transcription, or sequences bound by transcriptional activators to increase transcription

A

Operators

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5
Q

Activators bind to activator binding sites (sequence specific) to assist RNA polymerase binding

A

positive regulation

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6
Q

Repressors bind to operators (sequence-specific) to prevent RNA polymerase binding

A

negative regulation

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7
Q

Can bind to regulatory proteins to allow or prevent binding to DNA

A

allosteric effectors

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8
Q

Genes in an operon are transcribed as…

A

polycistronic RNAs

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9
Q

Bacterial exchange of DNA: partial genome transfer by DNA uptake

A

transformation

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10
Q

Bacterial exchange of DNA: plasmid transfer, results in partial genome transfer

A

Conjugation

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11
Q

Bacterial exchange of DNA: transfer as part of viral genome

A

transduction

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12
Q

Merodiploids

A

partial diploids resulting from conjugation

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13
Q

Negative Regulation of Lac Operon: is transcribed and translated continuously

A

Lac repressor (lacI)

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14
Q

Negative Regulation of Lac Operon: repressor binds to ____ of the operon and blocks transcription of lac operon genes

A

Lac operator (lacO)

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15
Q

Negative Regulation of Lac Operon: In the presence of the ______, the repressor undergoes a conformational change and can no longer bind to the operator

A

inducer (lactose, allolactose)

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16
Q

MUST be physically linked and spatially very close to the DNA that is regulated

A

cis

17
Q

a molecule that is separate from the DNA that is regulated

A

trans

18
Q

One mutation affects many things

A

pleiotrophy

19
Q
  • mutation of lacI makes lac operon genes constitutive
  • presence of functional lacI suppresses mutant phenotype (lacI- is recessive)
    -lacI is trans-acting (repressor protein is separate from lac operon)
A

Lac I findings from Pardee, Jacob, and Monod study

20
Q
  • Mutation of lacO makes lac operon genes constitutive
  • presence of functional lacO does not suppress mutant phenotype (lacOc is dominant)
  • lacO is cis-acting (sequence is within lac operon)
A

Lac O findings from Pardee, Jacob, and Monod study

21
Q

Positive regulation of the lac Operon: _____ activator that binds to the CAP binding site

A

Catabolite Activation Protein (CAP)

22
Q

Positive regulation of the lac Operon: CAP can bind to DNA when it is bound to ______

A

cAMP

23
Q

-araA, araB, and araD encode for enzymes that break down arabinsose
-araC encodes for an activator protein when bound to arabinose
-CAP-cAMP also activates this operon
- In absence of arabinose, araC binds both the I site and the O site to repress transcription

A

Regulation of the ara Operon

24
Q

contains genes that encode for enzymes that catalyze reactions needed for the production of tryptophan in E. coli

A

trp operon

25
Q

trp operon: tryptophan is a ________ that binds to a repressor and activates it through allosteric activation

A

corepressor

26
Q

trp operon enzymes are produced only when Trp levels are low and Trp production is thus needed

A

the trp Operon is Repressible

27
Q
  • contains a start codon and two codons that encode for tryptophan
  • RNA produced can base pair with itself to form a secondary structure
A

trp Operon leader sequence

28
Q
  • even in the presence of tryptophan, there is some level of transcription of the trp operon– but the transcripts are terminated prematurely
  • transcription is attenuated
  • formation of a stem loop in the mRNA determines transcription termination
  • ribosome stalling (waiting for tRNA-Trp) influences hairpin formation
A

Rate of translation affects trp Leader RNA structure

28
Q

attenuated

A

greatly reduced, not completely turned off

29
Q
  • Leader region is completely translated
  • formation of stem and loop in attenuator region results in the termination of transcription
A

High tryptophan level

30
Q
  • ribosome is stalled at trp codons in leader region
  • transcription continues
A

low tryptophan levels

Genetics (9 decks)

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