Chromosome Heredity & Transmission Genetics – Key Terminology

Regular flashcards covering fundamental vocabulary from Class 01 on chromosome heredity, transmission genetics, and basic probability principles.

Gene

A functional unit of heredity.

Allele

A form of a gene, most cases we will deal with two alleles in a gene.

Chromosome

The physical body that holds genetic material; a single long double-stranded DNA molecule.

Locus (plural: loci)

The position along a chromosome where a gene resides.

Diploid

Having two copies of the genetic material.

Haploid

Having only one copy of the genetic material.

Gamete

The unit of sex, germ cells like sperm or eggs. Gametes are haploid in diploid organisms.

Homologous chromosomes

A pair of chromosomes in a diploid individual.

Sister chromatids

After replication, the copies of each homologous chromosome.

Mitosis

A type of cell division that generates identical copies of DNA to each cell.

Meiosis

A type of cell division that halves the genetic content (e.g., diploid to haploid)

Homozygous

Having both alleles of a gene be the same (in a diploid individual).

Heterozygous

Both alleles of a gene are different (in a diploid)

Wild-type

The phenotype of a laboratory reference strain or the most common allele or of a phenotype in a population

Genotype

The genetic composition of an organism.

Phenotype

The expression of a genotype.

Trait

An aspect or character of the phenotype, such as height, color, or behavior.

Dominant

The phenotype observed in the offspring from a cross between parents with two different phenotypes

Recessive

Refers to a type of phenotype which will not be manifested in an individual unless both of the individual's copies of that gene have that particular allele.

Genetic Cross (or cross)

Mating between male and female gametes, can be either with two individuals or a self-cross when the individual makes both male and female gametes

True Breeding

A strain that, when crossed to itself, produces offspring identical to the parents; typically homozygous at all loci

Self-Cross

A cross in which the gametes come from the same individual.

Hybrid Cross

A cross between two heterozygous individuals.

Monohybrid Cross

A cross between organisms that are heterozygous for one gene.

Dihybrid Cross

A cross between organisms that are heterozygous for two loci.

Test Cross

A cross between a homozygous individual with the recessive phenotype and a parent with an unknown genotype