DQ 3-1-10

• What is a genotype?

• What is a phenotype?

• How many alleles for each gene does an organism have?

Turn in Spot the Dog worksheet, if not already turned in!

Punnett Squares

Practice

In guinea pigs, black is dominant

Cross a homozygous dominant with a heterozygous guinea pig.

In guinea pigs, black is dominant

Cross a homozygous recessive with a heterozygous.

In guinea pigs, black is dominant

Cross two heterozygous guinea pigs.

A codominant crossIn cattle, red hair and white hair are codominant – they will both show up if the cow is heterozygous. This mixed color is called roan.

Cross homozygous white with a homozygous red.

A codominant crossIn cattle, red hair and white hair are codominant – they will both show up if the cow is heterozygous. This mixed color is called roan.

Cross two heterozygous roans.

A codominant crossIn cattle, red hair and white hair are codominant – they will both show up if the cow is heterozygous. This mixed color is called roan.

Cross a homozygous dominant with a heterozygous roan.