Lethal allele

Lethal alleles punnett square

Lethal allele

A lethal allele is a type of allele that can cause the death of an organism, typically during the early stages of development. These alleles are usually the result of mutations in essential genes, which are necessary for survival. Lethal alleles can be either dominant or recessive, although recessive lethal alleles are more common.

Types of Lethal Alleles

Lethal alleles can be classified into several types based on their genetic behavior and the stage of development at which they cause lethality.

Recessive Lethal Alleles

Recessive lethal alleles only cause death when an organism is homozygous for the allele. In the heterozygous state, the organism can survive, often without any noticeable effects. An example of a recessive lethal allele is the Manx cat gene, which causes a shortened tail in heterozygous individuals but is lethal in the homozygous state.

Dominant Lethal Alleles

Dominant lethal alleles cause death when present in just one copy. These alleles are rare because they tend to be eliminated from the population quickly. An example of a dominant lethal allele is the allele responsible for Huntington's disease, which typically manifests later in life, allowing the allele to be passed on to offspring.

Mechanisms of Lethality

Lethal alleles can cause death through various mechanisms, including:

• Disruption of essential metabolic pathways
• Interference with critical developmental processes
• Induction of severe structural abnormalities

Detection and Study

Lethal alleles are often detected through genetic screening and breeding experiments. Researchers study lethal alleles to understand essential genes and their functions, as well as to gain insights into genetic disorders and evolutionary biology.

Examples in Model Organisms

Lethal alleles have been extensively studied in model organisms such as Drosophila melanogaster (fruit fly) and Mus musculus (house mouse). These studies have provided valuable information about gene function and genetic regulation.

Related Concepts

• Genetic linkage
• Epistasis
• Gene expression
• Mutation

See Also

• Allele
• Genotype
• Phenotype
• Genetic disorder
• Homozygous
• Heterozygous