12.2: Beyond Mendel's Laws of Inheritance

MATES Biotechnology, Sprague 2024

incomplete dominance

heterozygotes show an intermediate phenotype; some of the recessive gene makes itself visible

RR = red flowers

rr = white flowers

Rr = pink flowers

co-dominance

the heterozygote shows some aspect of the phenotype of both homozygotes

ex: human blood types

pleitropy

one gene affects multiple traits; an allele that has more than one effect on the phenotype

epistasis

one gene affects or controls the expression of another gene

ex: pigment alleles controlling if different colors will appear in the phenotype

polymorphism

a trait has more than one version; different versions of the same trait in a population

A, B, AB, and O blood types, or different colored moths—kinda like different flavors or ice cream

Thomas Hunt Morgan

discovered sex-linked traits—genes that are located on chromosomes

Why are calico cats only females?

They receive two X-chromosomes (only females) that each have orange and black coloring. In the genes, one of the two X chromosomes gets randomly “turned off.” The inactivated X chromosomes becomes a Barr body—other color shows.

Why are sex-linked traits more common in males?

Sex-linked traits like hemophilia and colorblindness cannot be subdued by another non-carrier X chromosome in males because they only have 1 X chromosome.