Lecture 10

Question 1

What are some potential points for regulation of gene expression? (7)

Answer 1

DNA rearrangement 
Initiation of transcription
Alternative splicing (eukaryotes only)
Export of RNA (eukaryotes only)
Stability of mRNA 
Initiation of translation
Post-translational control - modification of protein

Question 2

Where is the most important point for gene regulation?

Answer 2

Initiation of transcription

Question 3

What does regulation of gene expression involve?

Answer 3

cis-acting DNA sequences

Trans-acting protein factors

Question 4

What is the name given to genes that are always expressed and name some examples

Answer 4

Constitutively expressed

RNA polymerase, glycolysis enzymes

Question 5

What is the name of genes that are only expressed in certain circumstances? What can these genes be further subdivided into?

Answer 5

Regulatable

• inducible - usually off but can be switched on (lac operon E. coli)
• repressible - usually on but can be switched off (trp operon E. coli)

Question 6

How can it be concluded that expression of genes must be regulated in some way?

Answer 6

Vast majority of cells in a eukaryotic organism contai the same DNA but there are many different types of cells
A prokaryotic cell can express different genes under different growth conditions