2. Monohybrid, Dihybrid, and Sex-Linked Inheritance

Allele

An alternative version of a gene that differs by one or a few bases and occupies the same locus (position) on a chromosome.

Carrier

A person with a heterozygous genotype who possesses a recessive allele that is not expressed in their phenotype.

Dihybrid Cross

A genetic cross used to investigate the inheritance of two traits, controlled by two genes, simultaneously.

Diploid

A cell or nucleus containing two complete sets of chromosomes (2n), one from each parent.

Dominant Allele

An allele that has the same effect on the phenotype whether it is present in a homozygous or heterozygous state.

Gene

A heritable factor that consists of a length of DNA and influences a specific characteristic.

Genotype

The specific combination of alleles present in an organism.

Haploid

A cell (such as a gamete) containing only one set of chromosomes (n).

Heterozygous

An individual possessing two different alleles of a particular gene (e.g., Aa).

Homozygous

An individual possessing two identical alleles of a particular gene (e.g., AA or aa).

Locus

The specific position of a gene on a chromosome.

Monohybrid Cross

A genetic cross used to track the inheritance of a single trait.

Phenotype

The observable physical traits or characteristics of an organism, resulting from its genotype and environment.

Recessive Allele

An allele that only has an effect on the phenotype when present in the homozygous state.

Sex-linked

Genes located on a sex chromosome, typically the X-chromosome.

Zygote

The diploid cell resulting from the fusion of male and female haploid gametes.