A common feature of organisms is that offspring tend to look like their parents. For example, tall, brown-eyed parents tend to have tall, brown-eyed children. The mechanism by which parents pass on particular traits to their offspring is termed heredity. The focus of the following entry will be to explore the role of genes in heredity.

What Is a Gene?

Originally, most biologists believed in "blending inheritance," where the joining of a sperm from the father and an egg from the mother yields off-spring which have characteristics that are a blend of the characteristics of the two parents. However, Austrian botanist Gregor Mendel's (1822-1884) pioneering work with inheritance in pea plants largely disproved this theory. Mendel showed that for many traits, when a pea plant with one trait(e.g., green pods) is bred to a pea plant with another trait (e.g., yellow pods), the offspring always...