Lecture 3 - Synthetic biology for studying promoter evolution

Question 1

What constrains evolutionary potential?

Answer 1

Existing molecular mechanisms -

Question 2

Epistasis: what is it?

Answer 2

When the expression of one gene is affected by the expression of another gene

Positive epistasis - work with each other
Negative epistasis - don’t support each other (but still are ‘positive’)
No epistasis - just ‘add’ together - don’t interact with each other

Question 3

DME: what is it?

Answer 3

Distribution of mutational effects

Question 4

Reasons why epistasis and DME are typically negative

Answer 4

• Strong promoter - changing it isn’t often good
• Thermodynamics - changes that have a higher energy cost for binding results in reduced promoter binding