Glossary
The vocabulary of genetics, in plain words.
- Gene
- A stretch of DNA that carries the instructions for a functional product, usually a protein.
- Allele
- One of the alternative versions of a gene.
- Genotype
- The alleles an individual carries.
- Phenotype
- The observable characteristics that result from genotype and environment together.
- Dominant and recessive
- A dominant allele shows its effect with one copy; a recessive allele only with two.
- Chromosome
- A long DNA molecule with its packaging proteins. Humans have 23 pairs.
- Genome
- All the DNA of an organism — about three billion base pairs in a human.
- DNA
- Deoxyribonucleic acid: two complementary strands of four bases, A, C, G and T.
- RNA
- Ribonucleic acid: a single-stranded copy used to carry and regulate genetic information.
- Codon
- Three bases that specify one amino acid.
- Transcription and translation
- Copying DNA into RNA, then reading RNA to build a protein.
- Mutation
- A change in DNA sequence.
- Recombination
- The exchange of DNA between paired chromosomes when eggs and sperm form.
- Linkage
- The tendency of genes close together on a chromosome to be inherited together.
- Heritability
- The share of variation in a trait, within a population, that is due to genetic differences.
- Polygenic
- Influenced by many genes, each of small effect.
- Epigenetic mark
- A chemical tag on DNA or its proteins that affects gene activity without altering sequence.
- Genome editing
- Deliberately changing DNA at a chosen site.
- Variant
- A position where genomes differ; the neutral modern word for what used to be called a mutation or polymorphism.