Genetics — Mendel's Laws

Key terms:

Genotype — genetic makeup (AA, Aa, aa)

Phenotype — observable traits

Allele — version of a gene

Dominant — expressed when one copy present (A)

Recessive — expressed only when two copies present (aa)

Homozygous — two identical alleles (AA or aa)

Heterozygous — two different alleles (Aa)

Mendel's Laws:

Segregation — each gamete gets one allele of each gene

Independent Assortment — genes on different chromosomes assort independently

Monohybrid cross (Aa × Aa):

Genotype ratio: 1 AA : 2 Aa : 1 aa

Phenotype ratio: 3 dominant : 1 recessive

Non-Mendelian patterns:

Incomplete dominance — heterozygote is intermediate

Codominance — both alleles expressed (ABO blood type)

X-linked — gene on X chromosome; males (XY) more affected by recessive traits

Polygenic — multiple genes control one trait (height, skin color)

Reference:

Wikipedia: Mendelian Inheritance

https://en.wikipedia.org/wiki/Mendelian_inheritance