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Why do organisms as different as bacteria and humans share many chemical processes?
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Biology
A researcher using a microscope to examine a specimen in the laboratory.
Organisms as different as bacteria and humans share many chemical processes because they are related by descent from common ancestors. This fundamental unity of life indicates that all living things share a common origin.12
The molecular uniformity observed across diverse species provides compelling evidence for this shared history. Key examples of this commonality include:1
- Genetic Code: The genetic code—the "dictionary" used to translate DNA information into proteins—is virtually identical in all organisms.31
- Building Blocks: Despite the existence of many other possibilities, nearly all life uses the same 20 amino acids to construct proteins and the same four nucleotides to form DNA.31
- Metabolic Pathways: Similar biochemical reactions are employed across diverse life forms to produce energy and synthesize cellular components. For instance, the use of adenosine triphosphate (ATP) as a primary energy carrier is ubiquitous.13
These shared patterns are not strictly necessary from a chemical standpoint, suggesting that they are conserved traits inherited from a very few common cellular ancestors, or perhaps one.31