Unit 5 – Other forms of inheritance Not all traits are simply dominant or recessive, with only 2 possible alleles. Incomplete Dominance = BLENDING in heterozygotes.
Not all traits are simply dominant or recessive, with only 2 possible alleles.
Red = RRWhite = WWPink = RW
Genotype ratio: 100% heterozygous
Co-dominance = TOGETHER or SPOTTED – both traits are FULLY and SEPARATELY expressed
BB = Black
WW = White
BW = Black AND White hairs together
Cross a cow and a bull that have black and white hairs.
Phenotype: 25% Black, 25% white, 50% black and white
Genotype: 25% homozygous black, 25% homozygous white,
Some disorders are carried on the X chromosome. Examples of these disorders are color blindness, and hemophilia.
When doing Punnett Squares, you must first use sex chromosomes (XX for female, XY for male) then assign letters to the trait and put them as superscripts on the sex chromosomes.
Cross a heterozygous normal vision female with a normal vision male. (First cross sex chromosomes, then put on alleles and cross them).
50% Normal vision females25% Normal vision males
25% Color Blind males
Genotype: 25% XBXb (Carrier)
Human Blood Types: Use both co-dominance and regular dominant/recessive.
Cross a person who is homozygous for type A blood with a person who has type AB blood.
Phenotype Ratio: 50% Type A, 50% Type AB
Genotype Ratio: 50% AA, 50% AB