Exam 2: Ch 7 Control of Gene Expression in Bacteria Flashcards Preview

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Flashcards in Exam 2: Ch 7 Control of Gene Expression in Bacteria Deck (30):
1

in cancer, genes that restrain cell growth are ________ repressed and genes that encode proteins that promote cell growth and replication are ________ activated

abnormally, inapropriately

2

regulation of gene expression can occur at various steps

transcription initiation and elongation

RNA processing

mRNA export from nucleus

translation

3

control of gene expression at which two steps are most important for determining whether most genes are expressed and how much protein is produced?

transcription initiation and elongation

4

what is pax6

transcription factor that regulates transcription of genes involved in eye development

5

what do repressor and activator proteins do

recognize and bind to specific regions of DNA to control the transcription of a nearby gene

6

transcription control region

sequences of DNA that serve as binding sites for repressor and activator proteins

7

the structure and function of a cell are determined by ...

the proteins it contains

8

by controlling _____ a cell can regulate which proteins it produces, and how rapidly

transcription

9

when transcription of a gene is ______, the corresponding mRNA and encoded protein is synthesized at low rates. Opposite of this is...

repressed

activated

10

operons in E. coli

make up half the genes

encode enzymes involved in metabolic pathways or multiple proteins

11

what do the lac and trp operon encode?

lac: 3 proteins required for metabolism of lactose

trp: 5 pp needed for biosynthesis of tryptophan

12

coordinate regulation

all genes in an operon are activated or repressed to the same extent

13

transcription of operons and isolated genes is controlled by interplay between...

RNA polymerase and specific repressor and activator proteins

14

to initiate transcription, E. coli RNA polymerase must be associated with...

a sigma factor

σ70 binds RNA polymerase and to promoter DNA sequences

15

σ70 is...

an initiation factor

16

synthesis of the lac operon is repressed when....

there is no lactose around: to conserve energy

when there is glucose around: preferential glucose metabolism

17

transcription of lac operon under different conditions is controlled by...

lac repressor

catabolite activator protein (CAP)

both bind to a specific DNA sequence in the lac transcription control region called the operator and CAP site

18

when no lactose is present where does the lac repressor bind

to the lac promoter, blocking σ70 from initiating transcription

19

when glucose falls, E. coli synthesizes a lot of...

cyclic AMP that binds to CAP protein allowing it to bind to the CAP site, stimulating rate of transcription initiation

20

what makes a strong/weak promoter

rate of transcription

21

what regulates expression of many bacterial genes via DNA-binding repressors and activators

small molecules

cAMP, phosphorylation

22

how many σ factors are there

7

23

enhancer

binding sites in DNA located 80-160bp upstream from start site

24

σ54

sigma factor found in E. coli

binds to RNA polymerase to start transcription initiation

25

NtrC protein

stimulates transcription of glnA gene that encodes enzyme glutamine synthetase

binds to enhancer after being phosphorylated by NrtB

26

many bacterial responses are controlled by..

two-component regulatory systems

like NtrC and NtrB

27

control of transcription elongation example

trp operon

28

trp operon is repressed by

trp repressor when concentration of trp in cytoplasm is high

29

when there is low concentration of tRNAtrp...

the ribosome stalls at the 2 Trp codons in region 1

30

riboswitch

RNA tertiary structures that bind small molecules when present at high concentration

form hairpins that lead to early termination of transcription