Final answer:
A diploid individual with two different alleles of the same gene is known as a heterozygote. This concept is key to understanding phenotypes and genotypes in Mendelian inheritance patterns.
Step-by-step explanation:
A diploid individual carrying two different alleles of the same gene is best described as a heterozygote. In biology, alleles are different versions of a gene that exist at the same location on homologous chromosomes. An organism that has two identical alleles for a gene is homozygous, while one that has two different alleles is heterozygous. For genetic traits determined by a single gene, diploid organisms such as humans have two alleles, one from each parent. If these alleles differ, the organism exhibits a heterozygous genotype (e.g., Aa), which can result in various phenotype expressions due to dominant or recessive allele interactions.
For example, in Mendelian inheritance patterns, a pea plant with one allele for green peas and another for yellow peas would be considered heterozygous for that trait if the green and yellow alleles are different. In such cases, the phenotype might depend on whether the alleles show complete dominance, incomplete dominance, or codominance. Each of these patterns dictates how the organism's characteristics are expressed and can affect the organism's visible traits or phenotype, despite having a mixed underlying genetic makeup or genotype.