9. Influence of environmental factors on genotype and phenotype

Question 1

Expressivity

Answer 1

Degree to which a trait is expressed

Question 2

Example of Expressivity

Answer 2

Brachydactyly where the expressivity would be different size of digits in each individual with that disease.

Question 3

Penetrance

Answer 3

phenomenon where trait in one gene is expressed in one but not other individuals in that group.

Question 4

Example of penetrance

Answer 4

mutation in the BRCA1 or BRCA2 genes which cause cancer. Some people with the mutation never develop cancer , some do. Penetrance is variable.