W10 Gene expression regulation

Question 1

what is gene expression normally controlled by in unicellular organisms

Answer 1

environmental changes

Question 2

how is transcription initiated and regulated in prokaryotes

Answer 2

• at primary control point transcription of operons occurs
• RNA polymerase sigma factor binds to regulatory sequence

Question 3

what are operons

Answer 3

2 or more genes regulated by a promotor + terminator

Question 4

how is transcription terminated in cells

Answer 4

after the release of sigma factors and termination via rho protein/stable hairpin

Question 5

what is the role of tryptophan repressors

Answer 5

switch off genes

Question 6

what happens when tryptophan is low/high

Answer 6

low = operon is on so more transcription
high = operon is off so no transcription

Question 7

how can genes be turned on in prokaryotes

Answer 7

activators bind to bound activator proteins

Question 8

what is the Lac operon

Answer 8

negative inducible operon for lactose regulation

Question 9

what’s the role of the Lac operon

Answer 9

cleaves lactose into glucose and galactose

Question 10

what is used by prokaryotic cells glucose or lactose first

Answer 10

glucose

Question 11

what genes are on Lac operon for lactose regulation

Answer 11

gene Z, Y and A

Question 12

what condition turns on the Lac operon

Answer 12

low glucose and high lactose

Question 13

what can turn of the Lac operon

Answer 13

Lac repressor

Question 14

what are not found in eukaryotes that prokaryotes use for regulation of gen express

Answer 14

operons

Question 15

what’s the eukaryotic gene control region made of

Answer 15

promotor and cis-regulatory seqs

Question 16

how are genes in eukaryotes enabled

Answer 16

binding of coactivator for transcription

Question 17

how are genes in eukaryotes disabled

Answer 17

binding of co-repressor to stop transcription

Question 18

what do chromatin remodeling complexes make

Answer 18

histone chaperones

Question 19

what do histone chaperones do (2 things)

Answer 19

nucleosome removal/remodel
histone replacement

Question 20

how do transcription activators promote transcription

Answer 20

releasing RNA polymerase from the promotor region

Question 21

what do insulator elements do on eukaryotic DNA seqs

Answer 21

select domain of transcribed chromatin

Question 22

how can transcription be inhibited in eukaryotic cells

Answer 22

• comp DNA binding
• masking of activation surface
• use of chromatin remodelling complexes
• histone deacetylase
• histone methyl transferase

Question 23

can how nucleus be destroyed

Answer 23

using UV light

Question 24

what is the isoelectric point of a gene

Answer 24

pH where molecule has no charge

Question 25

what are 6 steps where gene expression can be controlled

Answer 25

• transcriptional control
• RNA processing control
• RNA transport control
• mRNA degradation control
• translation control
• protein activity control

Question 26

what are cis-regulatory seqs

Answer 26

where transcriptional regulators bind to

Question 27

how much of protein coding genes are transcriptional regulators

Answer 27

10%

Question 28

what are transcriptional regulators structural motifs

Answer 28

how the interaction between 2 helices affect the target repress gene

Question 29

what must a TF to turn on gene expression

Answer 29

dimserisation

Question 30

what are the contact points that transcriptional regulators share w DNA

Answer 30

ionic bonding
hydrogen bonding
hydrophobic interaction