Genetics College Biology

Gregor Mendel

• Mid 1800’s, Austrian monk.

• Introduced probability to genetics

• Mated pea plants

Cross-pollination

Produce seeds that have two different plants as parents

Traits

• Specific characteristic

Genes

• Chemical factors that determine traits

Alleles

• Different forms of the gene

The Principle of Dominance

• States that some alleles are dominant and others are recessive.

Law of Segregation

• Alleles for each trait are segregated from each other during the formation of sex cells, gametes.

Probability

• Likelihood that a particular event will occur.

Punnett Squares

• Used to predict and compare the genetic variations that will result from a cross

Homozygous

Two identical alleles

- Dominant: TT

- Recessive: tt

Heterozygous

• Two different alleles

Phenotype

• Physical characteristics

Genotype

• Genetic makeup

Law of Independent Assortment

• Genes of different traits can segregate independently of each other

• Dihybrid cross

Incomplete Dominance

• Heterozygous phenotypes are a mix of the two homozygous parents

Codominance

• Both alleles contribute to the phenotype

Multiple Alleles: more than two alleles

Polygenic Traits

• Having many genes that determine a trait

• Skin color, eye color