Heterozygosity

Heterozygosity refers to the state of having two different alleles at a particular locus in a diploid organism. This condition is a fundamental concept in genetics and is crucial for understanding genetic variation, evolution, and many medical conditions.

Overview

In genetics, an individual organism is said to be heterozygous at a gene locus when it has different alleles occupying that locus on a pair of homologous chromosomes. The term is derived from the Greek words "heteros" meaning different and "zygon" meaning yoke. Heterozygosity is contrasted with homozygosity, where an individual has the same allele at a locus on both homologous chromosomes.

Role in Genetic Variation

Heterozygosity plays a significant role in genetic variation, which is the basis for evolution. It allows for a wide range of phenotypes, or observable traits, in a population. This diversity can increase a population's ability to adapt to changing environments, a concept known as genetic diversity.

Medical Significance

In medicine, heterozygosity can have significant implications. For example, in autosomal dominant conditions, a person with one affected allele (heterozygous) will express the disease. In contrast, in autosomal recessive conditions, a person must have two affected alleles (homozygous) to express the disease. Heterozygous individuals are often carriers of the disease, meaning they can pass the affected allele to their offspring but do not express the disease themselves.

Heterozygosity and Evolution

Heterozygosity is also a key factor in evolution. It provides the genetic variation necessary for natural selection to occur. Populations with high heterozygosity are more likely to have individuals with the genetic traits necessary to survive and reproduce in changing environments.

See Also

• Homozygosity
• Genetic diversity
• Autosomal dominant
• Autosomal recessive

References

Heterozygosity Resources
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