Final answer:
The homology of the genetic code is an indication of common descent and the universal nature of the genetic code supports the idea of a common ancestor for all life on Earth. Its near-universality and resistance to change highlight the deep evolutionary roots and are important for biotechnological applications such as synthetic biology.
Step-by-step explanation:
The homology of the genetic code provides evidence of common descent among different species. This means that the genetic code is a homologous characteristic shared by all organisms, indicating that they share a common ancestor. The genetic code is nearly universal, with a few exceptions, and its conservation across wide varieties of life forms implies that it was established early in the evolutionary history of life on Earth. The possibility of transferring a gene like a messenger RNA molecule from one species to another and having it properly express the protein (for example, transferring horse globin mRNA to a tulip cell to synthesize horse globin) demonstrates the universal nature of the genetic code.
The degeneracy of the genetic code allowed for certain mutations to occur without affecting the amino acid being produced, which significantly reduced the potential impact of changes to the genetic code over time. This resistance to change adds to the evidence of a single, common origin for all life on Earth. Furthermore, the near-universality of the genetic code is important in applications like protein engineering and xenobiology, which are part of the growing field of synthetic biology, where organisms are engineered with modified genetic codes.