Glossary – Genes and their regulation

Use the alphabetical glossary below to remind yourself what the terms in the course mean.

Is there a term missing from the vocabulary used in the course? Tell me in the comments box below and I'll add it to the glossary.

Additive gene effect – each allele of a gene pair affects the individual’s appearance independently, neither masking nor attenuating the effect of the other. Also known as intermediate inheritance and codominance.

Allele – alternative form of a gene. Also called a variant.

Autosomal – located elsewhere than on the sex chromosome.

Autosome – chromosome other than a sex chromosome.

Base pairs – adenine-guanine (A-G) and cytosine-thymine (C-T), form the ladder rungs of the DNA chain.

Breeding – selection of the next generation of parent animals to change or maintain the characteristics of the animal population.

Chromosome – “home” of the genes; consists of a DNA strand.

Chromosome pair – pair of matching chromosomes from the sire and the dam.

Codominance – both alleles of a gene pair are expressed equally. Also called intermediate inheritance or additive gene effect.

DNA (deoxyribonucleic acid) – chain-like molecule that contains the genes of an individual. Packaged in each cell as chromosomes.

Dominant – blocks the expression of a recessive allele.

Egg – female gamete, a reproductive cell.

Epigenome – regulatory factors that influence the reading of an individual’s genes.

Gamete – reproductive cell; sperm or egg. An individual passes on its genes to its offspring through gametes.

Gene – recipe for a protein.

Gene pair – pair of alleles; one from the sire and another from the dam.

Genetic differences – different alleles.

Genetic diversity – diversity of alleles; genetic variation. Diversity is usually referred to as a characteristic of a population, not of a single individual. A single individual can have up to two different alleles per gene. In a population, there can be up to hundreds of different alleles of a gene.

Genome – the entire genetic material of an individual, all DNA.

Genotype – alleles of an individual in a particular gene or trait.

Heterozygous – gene pair containing two different alleles of a gene.

Homozygous – gene pair containing two identical alleles of a gene.

Imprinting – an imprinted gene only functions when inherited from the sire, or alternatively, only functions when inherited from the dam. As a result of imprinting, there is only one active allele in each cell.

Intermediate inheritance – see Codominance.

Locus – The “address” of a gene on a chromosome.

Mutation – change in the DNA code; a genetic error.

Phenotype – appearance of an individual, a visible characteristic.

Population – group of animals (or people).

Protein – building material of cells. Produces almost all the functions of the body.

Recessive – appears only if an individual has received the same allele from both its’ sire and dam. Masked by a dominant allele.

Sequence – order of the bases in the DNA code.

Sex-chromosomal – located on the sex chromosome.

Sex chromosome – X or Y chromosome.

Silencing – silencing of a chromosome or gene so that it cannot be read to form protein.

Somatic cell – cell other than a gamete.

Sperm – male gamete, a reproductive cell.

Stem cell – undifferentiated cell.

Variant – allele; alternative form of a gene.

Wild-type allele – normal, original allele; opposite of a mutant allele.

X chromosome – female sex chromosome.

X-linked inheritance – gene regulating a trait is located on the X chromosome.

Y chromosome – male sex chromosome.

Zygote – fertilised egg.


Is there a term missing from the vocabulary used in the course? Tell me in the comments box below and I’ll add it to the glossary.

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