Genetics: Terminology and Codominance

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  • Created by: tiacoles
  • Created on: 29-03-16 14:49

Genetic Terminology

Gene: A length of DNA that codes for the production (via mRNA) of one or more polypeptides or codes for the direct production of rRNA or tRNA. 

Allele: A variant form of a particular gene. There may be two, several or very many alleles of a gene. 

Genotype: The alleles present in an individual or cell

Genome: The sum total of genes in an organism

Phenotype: The expression of the alleles of the genotype, giving the individual's observable traits. 

Homozygote: A genotype in which the two alleles of a gene are identical e.g. AA or aa

Heterozygote: A genotype in which the two alleles of a gene are different e.g. Aa

Dominant Allele: Has the same effect on the phenotype when it is heterozygous or homozygous. It is symbolised by


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