Polygenetic Traits

Question 1

Continuous traits

Answer 1

traits that have a range of phenotypes, such as human height or eye colour with its many shades; is due to the polygenic effect of many genes together

Question 2

Polygenic inheritance

Answer 2

where more than one gene (often several) are involved in determining the phenotype for one characteristic (e.g., eye colour is actually the result of multiple genes that collectively contribute to the final eye colour)

Question 3

Epistasis

Answer 3

a type of polygenic inheritance where two genes collectively determine a phenotype of a trait (e.g., the B gene codes for type of colour (B = black, b = brown) and the C gene determines whether colour occurs at all (C = colour, c = no colour); three phenotypes result—white, brown, and black)

Question 4

Pleiotropy

Answer 4

the reverse of polygenic inheritance; where one gene affects the phenotypes for several traits (e.g., the PKU gene affects mental retardation, skin colour, hair colour, and other traits)