Allele

Author: Leandro Alegsa Creation date: November 13, 2022

An allele is a form of a gene at a particular position (locus) on a chromosome.¹⁵ It is the bit of coding DNA at that place.^p6

Typical plants and animals have two sets of chromosomes, one set inherited from each parent.¹²³ These organisms are called diploid. Since such organisms have two sets of chromosomes, they have (except on the sex chromosomes) two alleles at each gene locus.^p6

If the two alleles are identical, the individual is called a homozygote and is said to be homozygous. If instead the two alleles are different, the individual is a heterozygote and is heterozygous.²⁰⁵

Questions and Answers

Q: What is an allele?

A: An allele is a form of a gene at a particular position on a chromosome.

Q: How many sets of chromosomes do typical plants and animals have?

A: Typical plants and animals have two sets of chromosomes, one set inherited from each parent.

Q: Are organisms with two sets of chromosomes called diploid or haploid?

A: Organisms with two sets of chromosomes are called diploid.

Q: How many alleles do diploid organisms have at each gene locus (except on the sex chromosomes)?

A: Diploid organisms have two alleles at each gene locus (except on the sex chromosomes).

Q: What is a homozygote?

A: A homozygote is an individual with two identical alleles at a particular gene locus and is said to be homozygous.

Q: What is a heterozygote?

A: A heterozygote is an individual with two different alleles at a particular gene locus and is said to be heterozygous.

Q: Where is the bit of coding DNA located in an allele?

A: The bit of coding DNA in an allele is located at a particular position on a chromosome at a gene locus.