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Genetics > Lecture 9 > Flashcards

Lecture 9 Flashcards

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1
Q

In bacteria (but not eukaryotes) clusters of genes called ___ produce___ mRNA

A

Operons, polycistronic

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2
Q

Such groups of genes dedicated to the same biochemical pathway are called

A

Operons

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3
Q

is one mRNA for multiple genes/proteins

A

Polycistronic mRNA

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4
Q

In an operon, the start codon of each gene is preceded by a

A

Shine-Delgarno Sequence

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5
Q

Does eukaryotes contain Shine-Delgarno Sequence

A

No, except in mitochondria and chloroplasts

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6
Q

Breakdown of a substance, inducible

A

Catabolism

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7
Q

In E. coli and other bacteria, the Lac Operon encodes three enzymes that ___ lactose

A

catabolize

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8
Q

When lactose is NOT available to be metabolized, the lac operon is…

A

Shut down by lac repressor binding to lac operator and blocking transcriptional activation

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9
Q

When lac repressor binds operator, what happens to transcription of operon

A

No transcription

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10
Q

When exposed to lactose, a small portion is converted to __ that binds to the lac repressor,___ it.

A

allolactose, inactivating

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11
Q

What happens to transcription if glucose is present (basal transcription)

A

Low level

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12
Q

when glucose is also present in addition to the lactose, E. coli uses ___ first. The lac operon is transcribed ____because the CAP protein needed for high transcription is ___

A

glucose, only slightly, inactive

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13
Q

When CAP binds, what happens to transcription rate

A

It’s low

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14
Q

The absence of glucose causes _____ to accumulate.

A

cyclic AMP (cAMP)

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15
Q

When cAMP binds CAP and CAP binds CAP site, what happens to transcription?

A

Promotes transcription of lac operon

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16
Q

Biosynthesis of a substance , repressible

A

Anabolism

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17
Q

Ex ample of repressor + co-repressor:

A

Trp operon

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18
Q

When the amino acid tryptophan level is _____, the operon is transcribed in order to synthesize tryptophan

A

low

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19
Q

The trpR is expressed when?

A

All the time

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20
Q

When trp levels are low, what happens to transcription ?

A

Transcription of entire trp operon occurs

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21
Q

___tryptophan levels cause the Trp operon to be repressed

A

High

22
Q

In bacteria, genetic regulation is predominantly at the level of…

A

Transcription

23
Q

In Bacteria, regulation of gene expression can, alternatively, be…

A

Translational, posttranslational

24
Q

A protein can also bind outside the start
codon and act as a…

A

Translational repressor

25
Q

Translational repressor prevents ribosome from binding…

A

S-G sequence

26
Q

What RNA inhibits translation? What gene is used?

A

Antisense, micF gene

27
Q

binds the ompF RNA to prevent translation and reduce pores

A

MicF

28
Q

A common mechanism to regulate the activity of allosteric enzymes is

A

feedback inhibition

29
Q

Another way to control protein function is by the covalent modification of their structure.
Some modifications are ___

A

irreversible

30
Q

Proteolytic processing is what kind of modification

A

Irreversible

31
Q

Covalent modifications are what kind of modifications

A

Irreversible

32
Q

Methylation is what kind of modification

A

Reversible

33
Q

Acetylation is what kind of modification

A

Reversible

34
Q

Phosphorylation is what kind of modification

A

Reversible

35
Q

proteins that influence the
ability of RNA polymerase to transcribe a given gene

A

Transcription factors

36
Q

Required for the binding of the RNA pol to the core promoter and
its progression to the elongation stage

A

General transcription factors

37
Q

What is necessary for basal transcription?

A

General transcription factors

38
Q

They influence the ability of RNA pol to begin transcription of a particular gene

A

Regulatory transcription factors

39
Q

Transcription factor proteins contain regions, called ___, that have specific functions

A

Domains

40
Q

a domain or portion of a domain that has a very similar structure in many different proteins

A

Motif

41
Q

What motifs bind DNA

A

Helix-turn-helix motif & helix-loop-helix motif

42
Q

Composed of one a-helix and two b-sheets held together by a zinc (Zn++) metal ion

A

Zinc Finger Motif

43
Q

Two a-helices intertwined
due to leucine motifs, results in dimerization

A

Leucine zipper motif

44
Q

Tr anscriptional activators bind ___ to up-regulate transcription

A

enhancers

45
Q

The transcriptional activator up-regulates transcription by recruiting ___ and/or activating its function

A

TFIID

46
Q

Tr anscriptional repressors bind ___ to down-regulate transcription

A

Silencers

47
Q

The transcriptional repressor inhibits the binding of __ or inhibits its function.

A

TFIID

48
Q

Most enhancers and silencers are located within a few hundred nucleotides….

A

Upstream of the promoter

49
Q

links/bridges enhancers and silencers to core promotor

A

Mediator

50
Q

An effector molecule that activates an activating transcription factor is called an

A

Inducer molecule

51
Q

Inducer ____ repressor when bound

A

Inactivates

Genetics (11 decks)

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