Question

what does it mean when an organsim is a heterozygous?

Answer 1

It means that it has two different alleles. What does that mean? Well, an allele is a copy of a gene so different copies of a gene might produce differences in the organism such as flower colour, height of plant, eye colour in animals.

Other examples include disease alleles such as cystic fibrosis are encoded by mutated genes. This mutant allele can be carried in a heterozygote but when someone has two mutant copies they are homozygous and the disease is active because the person can't make any of the protein from the gene. I hope that helps, let me know if not. Best wishes