GENETICS Basic Heredity A study of gene inheritance from one generation to the next.

History of Heredity Gregor Mendel is father of modern genetics Mendel used pea plants to examine heredity from one generation to the next

Mendel’s Laws 1) Law of Segregation There are two factors controlling each trait These factors are “alleles” The alleles separate so that gametes only get 1 of the two alleles 2) Rule of Dominance One allele is always dominant over the other 3) Law of Independent Assortment

Genetics Rules Dominant alleles are written with CAPITAL letters Having 1 dominant alleles means the trait will be expressed Recessive alleles are written with lowercase Must have 2 recessive alleles for the trait to be expressed

Genotype vs. Phenotype Genotype: the alleles (letters) an individual has for a gene Phenotype: the way the genotype is expressed (looks)

Geno or Pheno? Tt HH Red hair BB Blue eyes

Homozygous: 2 of the same alleles for a gene (TT, tt, HH, etc) Heterozygous: 2 different alleles for a gene (Tt, Hh) Genotypes

Hetero or Homo? BB Bb Hh tt dD