Explain what it is about the origin of cells that makes it possible for proteins to be expressed by homologous genes to be functionally interchangeable in different organisms?

Answer 1

All living beings on Earth (and thus, all cells) are thought to be derived from a common ancestor. Solutions to many of the essential challenges that face a cell (such as the synthesis of proteins, lipids, and DNA) appear to have been achieved in this ancient common ancestor. The ancestral cell therefore possessed sets of proteins to carry out these essential functions. Many of the essential challenges facing modern-day cells are the same as those facing the ancestral cell, and the ancient solutions are often still effective. Thus, it is not uncommon for organisms to use proteins and biochemical pathways inherited from their ancestors. While these proteins often show some speciesspecific diversification, they still retain the basic biochemical characteristics of the

ancestral protein. For example, homologous proteins often retain their ability to interact with a specific protein target, even in diverse cell types. Because the basic biochemical characteristics are retained, homologous proteins are capable of functionally substituting for one another.