Key learning points

1. An individual inherits two copies of each gene in a pair of chromosomes.
2. Versions of genes are called alleles, they can be recessive or dominant, indicated with a capital or lowercase letter.
3. The combination of alleles that an organism has is called its genotype.
4. Different alleles of a gene are associated with different versions of the same characteristic called the phenotype.
5. Some phenotypes are determined only by genotype, others are also affected by the environment.

Keywords

• Allele - A genetic variant in a gene creates an allele (a different version of the gene), which produces a different phenotype.

• Dominant - One or both dominant alleles in the genotype for the characteristic to be expressed in the phenotype.

• Recessive - Two recessive alleles in the genotype for the characteristic to be expressed in the phenotype.

• Genotype - The combination of alleles an organism has for a characteristic (i.e. phenotype).

• Phenotype - Features that result, at least partly, from the genetic code of an organism’s genes.

Common misconception