L20-22: Gene Regulation

Question 1

define gene regulation

Answer 1

the rules and mechanisms controlling the expression of genes

Question 2

two types of genes

Answer 2

constitutive: always expressed + essential
contingency: encode products that confer advantage under special condition

Question 3

difference in gene regulation of prokaryotes and eukaryotes

Answer 3

1. purpose (p=growth, differentiation)
2. challenges (p= continual changes, constant enviro)
3. range (p= total switch off rare, common)
4. production of mrna

Question 4

4 ways cell can control protein production

Answer 4

1. transcriptional control (when gene is transpired )
2. rna processing control *how rna is spliced)
3. translational control (which mrnas are translated)
4. ppost- translational control (on/off after protein made)

Question 5

negative regulation

Answer 5

repressor protein= prevents transcitopion

Question 6

positive regulation

Answer 6

activator allows transcriptions

Question 7

define operon

Answer 7

genes adjacent - transcribed from single promotor into mRNA

Question 8

tryptophan operon

Answer 8

operon for aa trptophan production

Question 9

define promotor

Answer 9

DNA sequenceRNA polymerase binds to, open the DNA double helix, begin synthesising the mRNA.

Question 10

define operator

Answer 10

A short region of DNA to which the repressor protein binds; it controls the expression of the genes adjacent to it in the operon.

Question 11

define repressor

Answer 11

rotein that binds to an operator sequence to prevent transcription of the adjacent genes in the operon.

Question 12

define polycistronic mrna

Answer 12

RNA that has more than one coding region and is translated into a number of different proteins; formed when an operon is transcribed.

Question 13

difference of lac and trp operon

Answer 13

lac= catabolic

trp=anabolic

Question 14

what proteins carry out lactose metabolism

Answer 14

• galactosidase and lactose permease

Question 15

how does negative control of lac work

Answer 15

repressor protein binding to the operator and preventing RNA polymerase
from binding to the promoter : no transcription
 when lactose is present, its derivative allolactose acts as an inducer by binding to the repressor causing it to dissociate from the operator : transcription of the structural genes occurs

Question 16

is lac positive or negative control

Answer 16

both

Question 17

components of positive control of lac

Answer 17

lac promotor
activator (CAP)- helps rna polymerase bind to promotor
Cyclic AMP (cAMP)- CAP binds into cAMP first