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Flashcards in Prokaryotic gene regulation Deck (17):
1

what is the job of an activator gene?

- bind with complementary area of a promotor to activate RNA polymerase to transcribe the mRNA

2

what happens if the activator gene is degraded?

transcriptional induction of the operon is prevented

3

what is the job of the repressor gene?

inhibit transcription of an operon

4

what is an inducible operon?

usually off but can be stimulated

5

what does the lac operon code for?

functional genes which code for proteins that break down lactose

6

what happens when lactose is present?

Lactose binds to the repressor protein changing its shape so it can no longer bind and block RNA polymerase so it begins to transcribe the operon

7

which way does RNA polymerase transcribe?

from the 5 prime to 3 prime end

8

what codes for the lac 1 repressor protein?

the lac 1 repressor gene

9

what is the function of protein beta galactosidase?

mediates the hydrolysis of lactose by cutting the ester bond between the 2 disaccharide

10

what does the reduction is lactose result in?

less lactose to bind to repressor protein so it can regain its shape and bind to the promotor sequence blocking RNA polymerase

11

what is a repressible operon?

usually switched on but can be inhibited

12

what is the name of the repressor gene for the trp operon?

trpR

13

what does the trp operon code for?

proteins which bind together to form tryptophan

14

what does tryptophan do?

alters the inactive repressor protein to active so it can now bind and the trp operon is blocked from being expressed

15

how does tryptophan alter the shape of the repressor protein?

by binding to an allosteric site

16

what is the importance of tryptophan?

it is an essential amino acid but its levels must stay constant as increased levels have negative effects

17

what is positive feedback regulation?

genes are switched on in high densities in comparison to low cell densities where these genes would not be switched on