Adaptation
A physical or behavioural trait evolved to allow an organism to survive in its environment.
Allele
A version of a gene; the gene for eye colour, for instance, has several alleles.
Amino acid
An organic compound containing nitrogen; chains of amino acids form proteins.
Cell
The smallest self-contained unit of life, from which all organisms are formed.
Chromatid
A duplicated chromosome; chromatids usually pair together, but can also act as chromosomes on their own.
Chromosome
A carrier for genetic material found in the nucleus of cells of complex organisms.
Codon
A three-molecule unit in a gene that represents an amino acid within the larger protein molecule encoded by that gene. The anticodon is the mirror image of a codon, used in genetic coding.
Describing a cell that contains a double set of genetic material, with one set inherited from each parent.
DNA
Deoxyribonucleic acid, a ladder-like spiral molecule whose structure stores genetic information.
Endosymbiosis
A theory of how eukaryote cells evolved from smaller prokaryote cells living and working together.
Enzyme
A protein that is involved in metabolism by controlling a specific reaction needed for life.
Eukaryote
An organism with a body made from complex cells containing a nucleus and other organelles.
Evolution
The transformation of organisms over time through the interaction of outside influences and inherited traits.
Exon
A section of genetic material that carries code for a gene.
Fitness
How well an organism is suited to its environment compared to others of its species.
Gene
The unit of inheritance. It can be regarded as a strand of DNA that codes for a certain protein, or as a distinct hereditary characteristic.
Gene pool
The total accumulation of alleles found in a population.
Genome
The full collection of genetic material of a species, including genes and non-coding DNA.
Genotype
A description of the alleles carried by an organism.
Haploid
Describing a cell that contains only a single set of genes.
Intron
The section of inherited DNA that carries no coded instructions for genes.
Mendelian
Referring to the core ideas in genetics, formulated by Gregor Mendel in the 1860s.
Mutant
An organism that carries a novel allele, or mutated gene.
Nucleotide
A nucleic acid chemical found in DNA and RNA; In DNA the nucleotides frequently form pairs, while in RNA they are single.
Nucleus
The region of a eukaryotic cell containing most of its genetic material.
A machine-like structure in a cell that performs a particular set of functions.
Phenotype
A description of the physical and behavioural traits of an organism, as produced by a genotype.
Polymer
A long molecule made up of smaller units, or monomers, bonded together in a chain; proteins and DNA are both types of polymer.
Prokaryote
An organism with a small and simple cell that lacks organelles.
Protein
A complex molecule used by all living things to build structural body parts and muscle and as enzymes.
Respiration
The process that takes place in every living cell to extract energy from a food source, such as sugars.
Substrate
The material that is acted upon by an enzyme.
Taxonomy
The science of classifying organisms according to how they are related.
Zygote
The first cell of a living body.