Mendelian and Non-Mendelian Genetics: Key Concepts and Laws

Inheritance

Traits passed from parents to kids.

Gregor Mendel

Studied pea plants and understood that gametes were sex cells passed to offspring.

gametes

Sperm and eggs that provide a critical factor to the offspring.

Mendelian Inheritance

The inheritance patterns established by Gregor Mendel.

genetic cross

Experimentally mating organisms to produce offspring.

self-cross

Using one plant with both sexes to make offspring.

cross-breeding

Mating two organisms using two plants.

parental generation

Source of original gametes, abbreviated with P.

first generation

Offspring of the parental generation, abbreviated F1.

second generation

Offspring of the first generation, abbreviated F2.

phenotype

Physical appearance or traits of an organism.

genotype

Genetic type of an organism.

homozygous

Organism with two identical alleles for a trait.

heterozygous

Organism with two different alleles for a trait.

dominant allele

A trait that masks another, represented by uppercase letters.

recessive allele

A trait whose expression gets masked, represented by lowercase letters.

First Law: Law of Segregation

Each organism carries two alleles for each trait, which segregate during gamete formation, resulting in each gamete receiving one allele at random.

Second Law: The Law of Independent Assortment

Each factor segregates to different gametes independent of other factors.

factors

Genes that control traits in pea plants.

forms

Alleles that are genes on matching chromosomes coding for the same trait.

Non-Mendelian Inheritance

Inheritance patterns that do not follow Mendel's laws.

Incomplete Dominance

Traits appear to blend in heterozygotes.

Codominance

All versions of the trait are dominant, with no recessive.