Essential Knowledge 1.B.1 (3D GameLab)

One conserved core biological process is the use of DNA and RNA as the carriers of genetic information for all living organisms. With this, organisms share dependence on the transfer of information through transcription, translation, and DNA replication. The influence of DNA is observed particularly in nucleotides; all living organisms share the same four adenosine, cytosine, thymine, and guanine nucleotides, though their sequences (and thus, the amino acids and proteins for which they code) may differ extremely. A specific example of how this conserved core biological process works between organisms is the transformation of recombinant DNA so that the coded characteristics of one organism may be taken up by a different organism. This supports the idea of common ancestry because over time, and over the millions of years of evolution, we can understand how small phenotypic changes corresponding to small changes in gene sequence were passed over many generations.

Another conserved core biological process is the presence of mitochondria and/or chloroplasts in all eukaryotic cells. Both are organelles which support the processing of energy. The endosymbiont theory states that a prokaryotic cell that consumed oxygen and a photosynthetic prokaryotic cell were both ingested by the ancestor of the eukaryotic cell. There came to be an endosymbiotic relationship, or an equally beneficial relationship, between the host cell and its bacteria. The occurrence of this proposed relationship over millions of years supports the idea of common ancestry in that all eukaryotic cells came from this common ancestor cell with these organelles. Even the organelles evolved from prokaryotic bacterium to take on new functions.

Another conserved core biological process is the conservation of metabolic pathways across all currently recognized domains. One important example is the performance of glycolysis of cellular respiration across all organisms. Similarly, organisms that rely on photosynthesis have both light and dark reactions within their chloroplasts. Such similarities between organisms support the idea of common ancestry in that all eukaryotic cells depend on the same processes, a level even deeper than that of common organelles.