And these genes, these pairs of genes, or homologous genes, are also known as alleles. And what alleles are they're basically genes found on the two different homologous chromosomes that code for proteins that express that same type of trait. So these two genes, the purple genes, are alleles because they code for proteins that express that same high trait. These two are also alleles because they code for genes that code for another trait, let's say, the color of the seed and so forth. Now, what exactly do we mean by a heterozygous organism? So, an organism is heterozygous if one of these genes in the pair of alleles is a dominant gene for that given trait, and the other one is a recessive one.