Genes, Alleles, and Protein Subunits

What is a gene

A unit of heredity that contains information for a functional product, such as a polypeptide or functional RNA.

What is an allele

A version of a gene that differs in its DNA sequence.

How many alleles of a gene does a typical diploid individual have

Two, one inherited from each parent.

What does homozygous mean

Having two identical alleles of a gene.

What does heterozygous mean

Having two different alleles of a gene.

What is a dominant allele

An allele that determines the phenotype in a heterozygote.

What is a recessive allele

An allele whose phenotype is not expressed in a heterozygote when a dominant allele masks it.

Why can mutations in different genes produce the same phenotype

Different genes may encode proteins needed for the same pathway or biological function.

Why can a protein require more than one gene

Some proteins contain multiple polypeptide subunits, and different genes can encode different subunits.

What is an allelic mutation

A mutation in the same gene as another mutation being compared.

What is a non-allelic mutation

A mutation in a different gene from the other mutation being compared.