L20-22: Gene Regulation Flashcards Preview

SCIE1106 > L20-22: Gene Regulation > Flashcards

Flashcards in L20-22: Gene Regulation Deck (17)
Loading flashcards...
1

define gene regulation

the rules and mechanisms controlling the expression of genes

2

two types of genes

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

3

difference in gene regulation of prokaryotes and eukaryotes

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

4

4 ways cell can control protein production

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)

5

negative regulation

repressor protein= prevents transcitopion

6

positive regulation

activator allows transcriptions

7

define operon

genes adjacent - transcribed from single promotor into mRNA

8

tryptophan operon

operon for aa trptophan production

9

define promotor

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

10

define operator

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

11

define repressor

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

12

define polycistronic mrna

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

13

difference of lac and trp operon

lac= catabolic
trp=anabolic

14

what proteins carry out lactose metabolism

- galactosidase and lactose permease

15

how does negative control of lac work

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

16

is lac positive or negative control

both

17

components of positive control of lac

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