Punnett Squares

Gregor Mendel is known as the father of genetics

Gregor Mendel is an Austrian monk that studied in inheritance from 1856 to 1863

He ran an experiment with tall and short pea plants and came up with these laws:

• Traits are controlled by 2 factors

• Law of Dominance

• Law of Segregation

Homozygous/Purebred: 2 alleles for a gene are the same. AA= homozygous dominant, aa= homozygous recessive

Heterozygous/Hybrid: 2 alleles for a gene are different. Aa= heterozygous.

Meiosis:

• Cell division

• produces gametes (reproductive cells)

• half of the parent DNA

• Parent cells have 2 alleles for the trait that they have received from their parents

• Resulting daughter cells have only 1 allele for the trait

Meiosis vs Mitosis

• Mitosis produces body/somatic cells that have the exact same DNA as the parent cell. Meiosis has half of the DNA.

• Mitosis is used for genetic growth, repair, and development. Meiosis is used for reproduction.

Law of Segregation:

• Since 2 of the 4 daughter cells have the same DNA, one only needs to use 2 of the possible daughter cells in setting up a punnett square.