Non-Mendelian Genetics

Blood types There are three alleles that code for blood type A (IA) B (IB) O (i) A and B are codominant O is recessive to both A and B Results in 4 possible phenotypes for blood type: Blood type Possible Genotypes A IAIA or Iai B IBIB or IBi AB IAIB O ii

Sample problem #1 Both the father and mother have type AB blood Genotype of mother and father ______

Sample problem #2 A father is type A heterozygous and the mother is type B heterozygous Genotype of mother and father ______

Sex Chromosomes X Y

some genes are unique only to the Y chromosome X chromosome has over 1,000 genes most genes on the X chromosome do not have corresponding alleles on the Y chromosome Y chromosome has only a few dozen genes some genes are unique only to the Y chromosome

Sex-Linked Traits Those traits whose genes are found on the X chromosome but NOT on the Y chromosome Red-green colorblindness Male pattern baldness Hemophilia Muscular dystropy

Color Blindness “tests”

Females = XX –carry 2 alleles for a sex-linked trait Males = XY – only carry 1 allele for a sex-linked trait, so it is easier for them to get sex-linked diseases

Sex-Linked Traits, cont. Males receive sex-linked traits from their mother because their mother gives them the X chromosome and their father gives them the Y chromosome

Example of Sex-Linked Trait H = Normal blood clotting h = Hemophilia These will be written as a superscript next to the X and Y that represent the sex chromosomes

Example of Sex-Linked Trait Normal male: Male with Hemophilia: Normal female (not a carrier for hemophilia – homozygous): Normal female (carrier for hemophilia – heterozygous): Female with Hemophilia: XHY XhY XHXH XHXh XhXh

Sample problem #1. XHXh x XHY Chances of: a. hemophiliac child? b. hemophiliac son? c. hemophiliac daughter? d. daughter who is carrier? ¼ or 25% XH Xh XH Y XHXh XHXH ½ or 50% XHY XhY 0% ½ or 50%

2. A woman who is a carrier for hemophilia marries a hemophiliac man. XHXh x XhY Chances of: a. hemophiliac child? b. hemophiliac son? c. hemophiliac daughter? XH Xh 2/4 or 50% Xh Y XhXh XHXh ½ or 50% XHY XhY ½ or 50%