Genetic Variation IN 147 Headings Vocabulary Important Info

The Law of Segregation • Mendel’s 1 st Law • The 2 alleles of each gene pair separate into different gametes (egg or sperm) during meiosis.

The Law of Independent Assortment • Mendel’s 2 nd Law Independent Assortment: • Genes that are inherited separately… Do NOT influence the inheritance of others • Alleles segregate independently during meiosis • Some ALLELES go to one gamete and some to another

INCOMPLETE DOMINANCE Incompletely dominance: dominance • Genes are neither dominant nor recessive= they mix!!! mix • Genotype is heterozygous (hybrid--Hh) • Phenotype is between two parents • Dominant gene cannot fully mask the recessive • Ex: white flower x red flower = red pink flowers

CODOMINANCE Codominance: • Offspring shows phenotype of neither parent • Both alleles are DOMINANT!!! • Ex: black chicken x white chicken = checkered chicken

MULTIPLE ALLELES Multiple alleles: • Two OR More alleles control a trait • You still will only have two of these alleles. • Ex: height, hair color, eye color and blood type – There are 3 different alleles for blood: – (Type A) = IA IA or IA i – (Type B) = IB IB or IB i – (Type AB) = IA IB – (Type O) = ii

Sex-Linked Alleles Sex-linked alleles: • controlled by genes located on sex chromosomes (XX or XY) • Usually carried on X chromosome • Since females are XX, they are usually carriers of the trait • Since males are XY, they have a higher tendency for inheritance of trait

• If trait is X-linked, MALES: – pass it to all daughters – none to sons none • If trait is X-linked, MOTHERS: – have 50/50 chance of passing it to all of their children all • Ex: colorblindness, hemophilia, male pattern baldness