Genetics Key Terms 3: Allele Expression

Intergenic

Something that occurs between or involves more than one gene

Intragenic

An event that occurs within a gene itself

Intron

A DNA sequence that does not code or affect the RNA product, but still exists within a gene

Exon

A DNA sequence(s) that will be featured as a final product of RNA processes; expressed phenotype

Silent Mutation/Allele

A protein mutation that doesn’t affect the amino acid sequence of a coding protein, thus not affecting a protein’s function

Null Mutation/Allele

A protein mutation that affects an amino acid sequence and alters a protein’s function and potential coding results

Multiple Alleles

When more than two versions of a gene are present in a given population

Haplosufficient

When a single wild-type allele is sufficient for wild-type gene expression

Haploinsufficient

When one mutant gene is enough to cause a mutant gene expression; two wild-type alleles are needed for typical gene expression

Complete Dominance

When only one allele in a given genotype is expressed for (ie. all black hair)

Codominance

When both alleles in a genotype are equally expressed in a given individual (ie. sections of all white and all black hair)

Incomplete Dominance

When a mixture of alleles in a genotype are expressed in a certain combined form (ie. a combined output of black and white/gray hair)

Epistasis (or Gene Interaction)

When the effect of a gene mutation is influenced is influenced by the presence or absence of other gene mutations