Types Of Allele Expression

Question 0

Codominance

Answer 0

Two alleles fully express phenotypically, without masking in heterozygotic genotypes.

MN blood group.

Question 1

Incomplete dominance

Answer 1

Dominant allele is not completely dominant over recessive allele. Snapdragons, if homozygous, are red. If heterozygous, are pink.

Question 2

Multiple alleles

Answer 2

If there are more than one pair of potetial alleles that can exist in a genotype. Example: ABO blood group.

Question 3

Epistasis

Answer 3

When the alleles of one gene effect the phenotype of another.

Example: Labrador retrievers have two genes for fur color. When the fur color gene (B dominant for black, b recessive for chocolate) is homologous recessive while another gene E determines if that coloring is expressed at all. bbE(E/e) results in a chocolate lab.

Question 4

Polygenic inheritance

Answer 4

A trait is determined by many genes.

Example, height in humans. Also skin pigment.

Question 5

Pleiotropy

Answer 5

When one gene effect more than one character in an organism.

Example: sickle cell disease. PKU