Genetics

Heredity The passing of traits from parent to offspring.

What is a Gene again? A section of a chromosome that controls a specific trait.

Alleles Different forms of the same gene.  Example:  Widow’s peak  Each gene has two alleles…one from mom and one from dad.

Genetics The study of how traits are inherited through the interactions of alleles.

Genotype The alleles an individual has for a certain gene.

Phenotype The physical expression of an individual’s alleles.

Dominant and Recessive Alleles Alleles may be dominant or recessive.  Dominant alleles are always expressed in the phenotype.  Represented by a capital letter  Recessive alleles are covered up when paired with a dominant allele.  Represented by a small case letter

Homozygous Both alleles are the same (dominant or recessive).  TT  tt

Heterozygous One allele is dominant and one allele is recessive.  Tt

Gregor Mendel Father of genetics. Austrian monk. Performed experiments on pea plants.  Studied one trait at a time.  Kept careful records.  Applied mathematics.

Definitions Purebred  Always produce offspring that look like the parent. Hybrid  Offspring of parents with different forms of a trait.

Punnett Squares A mathematical way to determine probabilities in genetics.