Polygenic Inheritance

Question 1

Examples of Polygenic Traits

Answer 1

skin color (over 100 genes control skin color), eye color, height, etc.

Question 1

Polygenic Traits

Answer 1

traits that are controlled by several allelic pairs, which produces a continuous range of phenotypic variation, with each allele having an additive effect

Question 2

Multifactorial Trait

Answer 2

a condition that is caused by the interaction of multiple genes and environmental conditions

Question 3

Example of Multifactorial Traits

Answer 3

Himalayan Rabbits
– homozygous for melanin allele, but the enzyme coded for this gene only occurs at low temperatures, so dark fur is only present when the body temperature is lower

Also alcohol abuse disorders, phobias, suicidal behavior, etc.

Question 4

Codominance

Answer 4

occurs when alleles are equally expressed in a heterozygote
Ex. blood types

Question 5

Multiple Alleles

Answer 5

occurs when a gene exists with more than 2 allelic forms, however one person can still only have two of the possible alleles
Ex. human blood type

Question 6

Sex-linked

Answer 6

traits controlled by genes on the sex chromosome

Question 7

X-linked

Answer 7

alleles on the X chromosome
– most genes

Question 8

Y-linked

Answer 8

alleles on the Y chromosome

Question 9

X-linked Disorders

Answer 9

–color-blindness
– duchenne muscular dystrophy
– fragile X syndrome
– hemophilia