Life on Earth exists in a tremendous array of forms and features in almost every conceivable environment. Life is also characterized by adaptation: many organisms are exquisitely suited to the environment in which they are found. The history of life is a chronicle of new forms of life emerging, old forms disappearing, and existing forms changing.
Despite their tremendous diversity, living organisms have an important feature in common: all use similar genetic systems. The complete set of genetic instructions for any organism is its genome. All genomes are encoded in nucleic acids—
The fact that all organisms have similar genetic systems means that the study of one organism’s genes reveals principles that apply to other organisms. Investigations of how bacterial DNA is replicated (copied), for example, provide information that applies to the replication of human DNA. It also means that genes will function in foreign cells, which makes genetic engineering possible. Unfortunately, the similarity of genetic systems is also the basis for diseases such as AIDS (acquired immune deficiency syndrome), in which viral genes are able to function—
Life’s diversity and adaptation are products of evolution, which is simply genetic change over time. Evolution is a two-
Heredity affects many of our physical features as well as our susceptibility to many diseases and disorders. Genetics contributes to advances in agriculture, pharmaceuticals, and medicine and is fundamental to modern biology. All organisms use similar genetic systems, and genetic variation is the foundation of the diversity of all life.
CONCEPT CHECK 1
What are some of the implications of all organisms having similar genetic systems?
That all life forms are genetically related
That research findings on one organism’s gene function can often be applied to other organisms
That genes from one organism can often exist and thrive in another organism
All of the above
d