module 6 - 19.9 polygenic inheritance, epistasis & lethal genes

Question 1

what is polygenic inheritance?

Answer 1

when there are multiple alleles of 2 or more genes interacting with one another to influence phenotypic traits e.g. comb of poultry

Question 2

what is epistasis?

Answer 2

when multiple alleles of 2 or more genes interacting to influence of phenotypic traits and the presence of one gene suppresses the expression of another gene

Question 3

which genes is the epistatic/hypostatic gene?

Answer 3

epistatic - gene that does the suppressing
hypostatic - gene that is suppressed

Question 4

what does an epistatic gene do?

Answer 4

influence the activity of other genes as a result of the presence of dominant or recessive alleles

Question 5

when does dominant epistasis occur?

Answer 5

if a dominant allele results in a gene having an effect on another gene

Question 6

what are lethal genes?

Answer 6

• alleles that cause death when they are present in just a single copy
• allele leads to death of heterozygous before birth (e.g. yellow fur in mice is heterozygous and lethal so pure breeding yellow making homozygous yellow caused death)