What is represented by the term 'dominant allele'?

The term 'dominant allele' refers to an allele that expresses its phenotypic effect even when present in a heterozygous condition, meaning that it can influence the organism's appearance or characteristics regardless of whether the individual has one or two copies of that allele. When an individual has one copy of a dominant allele and another copy of a different allele (which may be recessive), the dominant allele will mask the effect of the recessive allele, thus determining the phenotype.

For example, in pea plants, the allele for purple flowers is dominant over the allele for white flowers. This means that a plant with one purple allele and one white allele will display purple flowers, showcasing the effect of the dominant allele.

In contrast, homozygous conditions refer to having two identical alleles for a specific gene, which does not apply to the definition of a dominant allele. Additionally, a dominant allele does not require a specific environmental factor for its expression; it is inherent to the genetic makeup of the organism. Overall, the ability of a dominant allele to affect the phenotype in both homozygous and heterozygous conditions is a fundamental concept in genetics, illustrating how dominant traits can be passed on and displayed in offspring.