Genetics of Organisms

An inheritance is something passed from one generation to another. In some contexts, this means stuff like houses and money. In the context of biology, however, the study of genes and how they are inherited, is called genetics. Gregor Mendel is credited with being the father of modern genetics. His work is responsible for our understanding of how noticeable physical traits, or phenotypes, are passed from one generation to the next. Famously, he studied such traits in pea plants.

The pieces of information controlling those phenotypes are called genes. As there are two copies of each gene, known as alleles, we can represent these as letters. Here, we'll use the letter P. This is the first step of Mendel's famous experiment on pea flower coloration, represented here, using a tool called the Punnett square. Mendel found that when he crossed purple flowers with white ones, all of the progeny, or the first-generation plants, had purple flowers. This is because the purple color is dominant, shown using uppercase P. And carrying even one dominant allele means the phenotype will be expressed. But interestingly, when these purple flowers were crossed again, 1/4 of them were white. Where were