GENETICS REVIEW• We get our genes from our parents – Half from our mom & half from our dad• Genes are represented by 2 letters – This is the genotype – Each letter can be capital (dominant) or lower case (recessive) – Genotypes can be homozygous or heterozygous – Homozygous – 2 letters are the same • Example: HH or hh – Heterozygous – the 2 letters are different • Example - Hh
GENETICS REVIEW, continued• Phenotype – tells how the genes look – Example, eye color – blue is recessive (b) – Brown is dominant (B)• BB is a homozygous genotype --- the phenotype is BROWN• Bb is a heterozygous genotype --- the phenotype is BROWN• bb is a homozygous genotype --- the phenotype is BLUE
GENETICS REVIEW, CONTINUED • We can predict the possible traits show with Punnett Squares • Break the genotypes up, put each letter over the top or down the side • Then you drag each letter down into each boxWhat is the B Bchance of a man Zero percent bwith blue eyes chance. In order Bb Bb for blue eyes toand a femalewith brown eyes appear you need 2(homozygote) Bb Bb recessive alleles. bhaving a blue The female on haseyed child? 2 dominant alleles.