Principles of Genetics (Chapter 1-3)

Phenotype

Physical or physiological traits.

Inheritance

Passing phenotypes from parent to offspring through reproduction.

Evolution

Changes in phenotypes over time.

Gene

A segment of DNA that codes for a functional product that influences a phenotype.

Mutation

DNA changes leading to new or altered genes/traits that contribute to evolution.

Oogenesis

A diploid cell produces one haploid cell (cytokinesis is unequal, eggs are larger than sperm).

Blending Hypothesis of Genetics

Offspring have intermediate traits of parents (refuted by Mendel’s pea plants, not always that simple).

Hybridization (Cross)

Two parent plants with distinct phenotypes are bred.

True-breeding parents

The parental (P) generation in hybridization.

Recessive Traits

Appears only when two recessive allies are present.

Dominant Traits

Appears when only one dominant allele is present.

Law of Segregation

If an individual has two copies of a gene they separate during the process that gives rise to gametes (meiosis).

Homozygous

An organism has two of the same alleles.

Heterozygous (Carriers)

An organism has copy of two different alleles. (Ex. Rr) Carries recessive allele, but doesn’t express the phenotype.

Homozygous Dominant

An organism carries two dominant copies of an allele.

Homozygous Recessive

An organism carries two recessive copies of an allele.

Monohybrid Cross

One gene/trait is being evaluated (Ex. height, flower color, etc.)

Dihybird Cross

Two genes/traits are being evaluated (Ex. Seed shape and color).