What are genes defined as in relation to heredity?

Genes are defined as biochemical units of heredity because they are the fundamental units that carry genetic information necessary for the development, functioning, growth, and reproduction of all living organisms. They are composed of DNA and serve as instructions for making proteins, which perform a wide range of functions within an organism. Each gene contributes to an individual's traits by encoding the specific sequences of amino acids that make up proteins, which in turn influence phenotype—observable characteristics that can be inherited from one generation to the next.

In the context of heredity, genes are passed from parents to offspring, thereby impacting the traits and characteristics of the next generation. This transfer of genetic information is a cornerstone of biological inheritance, distinguishing genes as crucial components in the study of genetics and evolution.