Regulation of Gene Expression

Question 1

What level gene regulated?

Answer 1

1) Transcript present?
2) Transcript structure?
3) Protein expressed?

Question 2

Transformer gene

- female development

Answer 2

Male = off Female = on

• transcript in both
• translated only in females
• females = splicing –> transcript
• males = stop codon –> no transcript

Question 3

Regulatory Sequence

Answer 3

Bacteria

• Positive = activator
• Negative = operator

Eukaryote

• Positive = enhancer
• Negative = silencer

Question 4

Promoter

Answer 4

Promoter = (+) prokaryote (-) eukaryote
Promoter & operator = (-) prokaryote (-) eukaryote
Promoter & activator = (+) prokaryote (+) eukaryote
Promoter, operator, activator = (-) prokaryote (-) eukaryote

Question 5

LacZ and Laci

Answer 5

Laci has diffusible factor = trans-acting to LacZ

Operator LacZ recognize diffusible factor = cis acting to LacZ

Question 6

Complementation Test

Answer 6

Mutations in different genes
- trans acting

Mutations in same genes
- cis acting

Question 7

Intragenic Analysis

Answer 7

• operator constitutive dominant to lacZ loss of function in trans
• wild type alleles dominant when operator constitutive and lacZ loss of function in cis

Question 8

Transcription Activators

Answer 8

binds to enhancer and silencers

- activate transcription

Question 9

Sex Lethal Protein

Answer 9

• blocks use of male 3’ ss
• alternative splicing
• only females have this protein
• males have no sex lethal protein – stop codon

Question 10

Nanos

Answer 10

• suppresses HB protein expression
• nanos null = expression
• binds to pumilio

Question 11

Pumilio

Answer 11

• suppresses HB protein expression

- binds to nanos regulatory element