Genetics:Basics

Question 1

What is classical dominance?

Answer 1

dominant gene is expresses

CC and Cr express dominant “C” phenotype

cc expresses recessive phenotype

Question 2

What is incomplete dominance?

Answer 2

phenotype is a mix of both alleles

e.g. pink flowers

R=red and r=white

W=white

RW -> pink

Question 3

What is co-dominance?

Answer 3

two alleles are expressed and neither is dominant

eg. ABO blood type

I^A = A antigen

I^B = B antigen

i = neither

Person with I^AI^Bgenotype is AB phenotype

I^Ai is A phenotype

Question 4

What is pleiotropism?

Answer 4

many traits affected by one gene

Question 5

What are polygenic traits?

Answer 5

complex traits affected by several genes

eg height

Question 6

What is penetrance?

Answer 6

the likelihood a person with a genotype will express the expected phenotype

penetrance can be affected by environmental factors

Question 7

What is epistasis?

Answer 7

expression of alleles for one gene depend upon a different gene

eg curly hair gene vs baldness gene