Gregor Mendel Father of Genetics Monk and teacher. Discovered some of the basic laws of heredity. Called the stronger hereditary factor dominant. Called the weaker hereditary factor recessive.

Mendel crossed purebred tall plants with purebred short plants and the first generation plants were all tall. When these tall offspring were crossed the result was a ratio of 3 tall to 1 short.

Dominant Traits RULE Mendel called stronger traits Dominant traits are represented by capital letters (T) while recessive traits are represented by lower case letters (t). Strong Hereditary traits cover weak traits. Mendel called stronger traits DOMINANT Mendel called weaker traits recessive

Predicting Inheritance To determine the chances of inheriting a given trait, scientists use Punnett squares and symbols to represent the genes. UPPERCASE letters are used to represent dominant genes. lowercase letters are used to represent recessive genes.

Punnett Square Tall homozygous dominant plant with homozygous short plant.

Punnett Square Mixing two heterozygous plants