Week 4: Control of gene expression

Question 1

What is tissue specific expression?

Answer 1

• different types of cells produce different sets of proteins (immunocytochemistry)

Question 2

What is polyphenism?

Answer 2

• where single clones of animals have different morphologies between them that have different roles

Question 3

What do the different types of RNA polymerase do?

Answer 3

• RNA polymerase I: transcribes ribosomal RNA
• RNA polymerase II: transcribes all protein encoding genes
• RNA polymerase III: transcribes tRNA and other small RNAs

Question 4

What are promotor and enhancer sequences?

Answer 4

• promotor sequence: very close to the protein coding region, has an initiator site and a ‘TATA’ box
• enhancer sequence: regulatory sites that can be distant from the promotor

Question 5

Which transcription factor binds to what?

Answer 5

• basal factors bind to promotor sequ.
• activators and repressors bind to enhancer sequ.

Question 6

Define epigenetics.

Answer 6

heritable changes in gene expression that do not involve changes in the DNA sequence

Question 7

Describe bacterial gene expression. (4 pts)

Answer 7

• no nuclear membrane
• one cytoplasmic compartment
• both translation and transcription occur simultaneously
• genes of related functions cluster into operons