# Gene

> A gene is a stretch of DNA that carries the instructions for one functional product, usually a protein such as an enzyme, and is the basic unit of inheritance.

- Canonical: https://genetixbay.com/knowledge/glossary/gene.html
- Also written: genes, genetic factor, hereditary unit
- Glossary category: Genetics and breeding · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

A gene is a [stretch](https://genetixbay.com/knowledge/glossary/stretch.md) of DNA that codes for one functional product, usually a protein. In cannabis many of the genes breeders care about code for enzymes: [THCA synthase](https://genetixbay.com/knowledge/glossary/thca-synthase.md), [CBDA synthase](https://genetixbay.com/knowledge/glossary/cbda-synthase.md) and the [terpene](https://genetixbay.com/knowledge/glossary/terpene.md) synthases that set aroma. Each gene sits at a fixed position on a chromosome, and a [diploid plant](https://genetixbay.com/knowledge/glossary/diploid.md) carries two copies of it, one from each parent.

## In practice

Growers use "gene" loosely to mean "the genetics" of a plant. Breeders use it precisely. When a breeder says "the [CBD](https://genetixbay.com/knowledge/glossary/cbd.md) gene is codominant", they mean the CBDA synthase gene at one locus, whose two versions ([alleles](https://genetixbay.com/knowledge/glossary/allele.md)) both show in the plant. Most traits growers select for (yield, vigour, resin density, flowering time) are not one gene but many genes acting together, plus the environment.

## Don't confuse with

- **Allele**: a version of a gene. "Gene" is the slot; "allele" is what fills it.
- **Genetics**: the whole inherited make-up of a plant, or the science. "Good genetics" means a good [genotype](https://genetixbay.com/knowledge/glossary/genotype.md), not one gene.
- **Strain**: a market name. It says nothing reliable about which genes a plant carries.

## Related terms

[Allele](https://genetixbay.com/knowledge/glossary/allele.md), [Locus](https://genetixbay.com/knowledge/glossary/locus.md), [Chromosome](https://genetixbay.com/knowledge/glossary/chromosome.md), [Genotype](https://genetixbay.com/knowledge/glossary/genotype.md), [Mutation](https://genetixbay.com/knowledge/glossary/mutation.md)

## Read more

- [Mendelian genetics for growers, with Punnett squares](https://genetixbay.com/knowledge/breeding/mendelian-genetics-for-growers.md)

## Sources

1. Acquaah G. 2012. Principles of Plant Genetics and Breeding, 2nd edition. Wiley-Blackwell. https://doi.org/10.1002/9781118313718
2. Laverty KU, Stout JM, Sullivan MJ, et al. 2019. A physical and genetic map of Cannabis sativa identifies extensive rearrangements at the THC/CBD acid synthase loci. Genome Research 29(1):146-156. https://doi.org/10.1101/gr.242594.118