Figure 15.1 Genes, which are carried on chromosomes (a), are linearly organized instructions for making the RNA and protein molecules that are necessary for all of processes of life. The interleukin-2 protein (b) and alpha-2-microglobulin protein (c) are just two examples of the array of different molecular structures that are encoded by genes. [credit (chromosome): National Human Genome Research Institute; credit (interleukin-2): Ramin Herati/Created from PDB 1M47 and rendered with Pymol; credit (alpha-2-microglobulin): Darren Logan/rendered with AISMIG]

The definition of gene has progressed from being an abstract unit of heredity in Gregor Mendel’s time to our current concept of a tangible molecular entity capable of replication, expression, and mutation (Figure 15.1). Currently, we can perform tests for many genetic diseases, but these tests create ethical and legal issues. For example, would you want to be tested for a debilitating genetic disease if there was the possibility insurance companies could use that information to deny you coverage? Fortunately, the Genetic Information Nondiscrimination Act of 2008 protects American citizens from discrimination from both insurance companies and employers based on genetic information. More information about policy, legal, and ethical issues in genetic research can be found at the National Human Genome Research Institute.