Key Terms & Phrases

Question 1

Synergistic heterozygosity

Answer 1

disease resulting from multiple partial defects in one or more metabolic pathways

Question 2

Dominant negative mutation

Answer 2

A mutation whose gene product adversely affects the normal, wild-type gene product within the same cell. This usually occurs if the product can still interact with the same elements as the wild-type product, but block some aspect of its function.

Example - A mutation in a transcription factor that removes the activation domain, but still contains the DNA binding domain.

Question 3

Mutations involving protein-coding genes cause disease through 1 of 4 different effects on protein function

Answer 3

• loss of function (thalassemias)
• gain of function - most commonly due to increased gene dosage (i.e. Down’s)
• novelty property mutations (i.e. Sickle cell)
• heterochronic expression (gene expression at the wrong time) and/or ectopic expression - gene expression in the wrong place - oncogene

Question 4

Four possible effects of a mutation on protein function

Answer 4

Loss of function
Gain of function
Novel property mutations
Mutations assoc w/Heterochronic expression - gene expressed at wrong time or Ectopic expression - expressed in wrong location