Lecture 9

Question 1

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

Answer 1

Operons, polycistronic

Question 2

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

Answer 2

Operons

Question 3

is one mRNA for multiple genes/proteins

Answer 3

Polycistronic mRNA

Question 4

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

Answer 4

Shine-Delgarno Sequence

Question 5

Does eukaryotes contain Shine-Delgarno Sequence

Answer 5

No, except in mitochondria and chloroplasts

Question 6

Breakdown of a substance, inducible

Answer 6

Catabolism

Question 7

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

Answer 7

catabolize

Question 8

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

Answer 8

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

Question 9

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

Answer 9

No transcription

Question 10

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

Answer 10

allolactose, inactivating

Question 11

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

Answer 11

Low level

Question 12

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 ___

Answer 12

glucose, only slightly, inactive

Question 13

When CAP binds, what happens to transcription rate

Answer 13

It’s low

Question 14

The absence of glucose causes _____ to accumulate.

Answer 14

cyclic AMP (cAMP)

Question 15

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

Answer 15

Promotes transcription of lac operon

Question 16

Biosynthesis of a substance , repressible

Answer 16

Anabolism

Question 17

Ex ample of repressor + co-repressor:

Answer 17

Trp operon

Question 18

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

Answer 18

low

Question 19

The trpR is expressed when?

Answer 19

All the time

Question 20

When trp levels are low, what happens to transcription ?

Answer 20

Transcription of entire trp operon occurs

Question 21

___tryptophan levels cause the Trp operon to be repressed

Answer 21

High

Question 22

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

Answer 22

Transcription

Question 23

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

Answer 23

Translational, posttranslational

Question 24

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

Answer 24

Translational repressor

Question 25

Translational repressor prevents ribosome from binding…

Answer 25

S-G sequence

Question 26

What RNA inhibits translation? What gene is used?

Answer 26

Antisense, micF gene

Question 27

binds the ompF RNA to prevent translation and reduce pores

Answer 27

MicF

Question 28

A common mechanism to regulate the activity of allosteric enzymes is

Answer 28

feedback inhibition

Question 29

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

Answer 29

irreversible

Question 30

Proteolytic processing is what kind of modification

Answer 30

Irreversible

Question 31

Covalent modifications are what kind of modifications

Answer 31

Irreversible

Question 32

Methylation is what kind of modification

Answer 32

Reversible

Question 33

Acetylation is what kind of modification

Answer 33

Reversible

Question 34

Phosphorylation is what kind of modification

Answer 34

Reversible

Question 35

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

Answer 35

Transcription factors

Question 36

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

Answer 36

General transcription factors

Question 37

What is necessary for basal transcription?

Answer 37

General transcription factors

Question 38

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

Answer 38

Regulatory transcription factors

Question 39

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

Answer 39

Domains

Question 40

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

Answer 40

Motif

Question 41

What motifs bind DNA

Answer 41

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

Question 42

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

Answer 42

Zinc Finger Motif

Question 43

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

Answer 43

Leucine zipper motif

Question 44

Tr anscriptional activators bind ___ to up-regulate transcription

Answer 44

enhancers

Question 45

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

Answer 45

TFIID

Question 46

Tr anscriptional repressors bind ___ to down-regulate transcription

Answer 46

Silencers

Question 47

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

Answer 47

TFIID

Question 48

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

Answer 48

Upstream of the promoter

Question 49

links/bridges enhancers and silencers to core promotor

Answer 49

Mediator

Question 50

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

Answer 50

Inducer molecule

Question 51

Inducer ____ repressor when bound

Answer 51

Inactivates