Objective: What is the purpose of a test- cross in genetics? Do Now: Black hair: B Blonde hair: b What would the gene combination look like for someone who is homozygous dominant for the trait?

Genotype Genotype: the genetic makeup of an organism, or the combination of alleles (ex: BB)

Phenotype Phenotype: Physical appearance of an organism, an observable trait (ex: black hair)

Punnett Square -A genetic cross that shows all possible outcomes of offspring

Test Cross -Breeds an individual of unknown genotype, but dominant phenotype with a homozygous recessive individual - Ex: Are you Bb or BB? Perform a test cross with a bb to determine the possibilities! Lets say you have Black hair…do you know your genotype? How could we figure out what your genotype is?

Law of Segregation

Law of Independent Assortment

Law of segregation: When a parent forms sex cells (egg or sperm), the parent’s gene pairs separate, so the sex cells carry only 1 allele for a particular trait Law of independent assortment: gene pairs are inherited independently of the gene pairs for all other traits. Law of Dominance: Only need to inherit 1 dominant allele to show trait

Dihybrid Cross A cross between organisms that differ in TWO characteristics (seed shape and seed color in pea plants)