What is the result of having two different alleles for a trait?

Having two different alleles for a trait is defined as being heterozygous. In genetics, alleles are variations of a gene that can produce different traits. When an organism has two different alleles at a particular gene locus, it is labeled as heterozygous, which often results in a phenotype that is a mix of both alleles, or in some cases, one allele can be dominant over the other.

This distinction is important because it helps in understanding inheritance patterns and the expression of traits. For example, if one allele carries the information for brown eyes and the other for blue, a heterozygous individual may display brown eyes if the brown allele is dominant.

The term homozygous refers to having two identical alleles for a trait, thereby representing the opposite of being heterozygous. Co-dominant refers to a situation where both alleles in a heterozygote manifest equally in the phenotype, while dominant describes an allele's ability to mask the effect of a recessive allele in heterozygous pairings.