What is the difference between a gene and an allele?

A gene is a segment of DNA that codes for a specific trait, while an allele is a variant form of a gene.

Genes are the basic units of heredity that determine the characteristics of an organism. They are composed of DNA and are located on chromosomes. Each gene codes for a specific trait, such as eye color or blood type. Genes can have multiple alleles, which are different versions of the same gene that produce variations in the trait.

Alleles are alternative forms of a gene that arise by mutation and are found at the same locus on a chromosome. For example, the gene for eye color has different alleles that produce blue, green, or brown eyes. Alleles can be dominant or recessive, meaning that one allele may mask the expression of the other.

The combination of alleles inherited from each parent determines an individual's genotype, or genetic makeup. The expression of the genotype in the physical characteristics of an organism is called the phenotype. The study of genes and alleles is known as genetics, and it plays a crucial role in understanding inheritance, evolution, and genetic disorders.