Molecules of Life

Is there a reason all amino acids in biological systems share the same chirality?

While the answer to this question is uncertain, there have been some interesting developments in this area. It has been shown that life (as it exists today anyway) cannot arise from a racemic mixture of amino acids because the presence of chiral centers in many biomolecules is crucial for biological function. The self-replication of DNA relies on the presence of chiral centers and without a shared chirality, the error rate in DNA replication would cause severe problems for many longer-lived plants and animals. One hypothesis for the origin of chirality is that molecules from outer space reached Earth with a net chirality already present. Another is that the net chirality in amino acids was established on Earth in a very short period of time. It’s a pretty interesting thing to think about, and this topic is a subject of ongoing research and debate.


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