Introduction: How Is Genetic Information Passed between Organisms?

Drosophila melanogaster.

Inheritance is the passing of traits from parents to offspring. Our modern understanding of inheritance comes from a set of principles proposed by Austrian monk and researcher Gregor Mendel in 1865. Interestingly, Mendel didn't arrive at these principles by studying human beings, but rather by studying the common pea plant, Pisum sativum. Although scientists now know that there are many exceptions to the patterns Mendel described, these principles describe the simplest mechanisms of inheritance. Moreover, because these so-called principles of Mendelian genetics hold true for organisms of many different types (including humans), they serve as the foundation for scientists' current understanding of heredity.

This unit takes a closer look at the concept of inheritance. It begins with a description of Mendel's basic principles, each of which is illustrated with the fruit fly Drosophila melanogaster, an insect that is widely used in the field of modern genetics. The unit then examines how variability in inheritance patterns can help researchers understand and test relationships between genes. Finally, the unit concludes with a discussion of how inheritance can involve different mechanisms in different organisms, including bacteria.