Peptide (from Gr. πεπτός, "digested", derived from πέσσειν, "to digest") are naturally occurring biological molecules. They are short chains of amino acid monomers linked by peptide (amide) bonds. The covalent chemical bonds are formed when the carboxyl group of one amino acid reacts with the amino group of another. The shortest peptides are dipeptides, consisting of 2 amino acids joined by a single peptide bond, followed by tripeptides, tetrapeptides, etc. A polypeptide is a long, continuous, and unbranched peptide chain. Hence, peptides fall under the broad chemical classes of biological oligomers and polymers, alongside nucleic acids, oligo- and polysaccharides, etc.
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- Darwinian evolution is most unlikely to get even one polypeptide [chain of essential life substances] right, let alone the thousands on which living cells depend for survival. This situation is well known to geneticists and yet nobody seems to blow the whistle decisively on the theory.
- Fred Hoyle and Chandra Wickramasinghe in their book Evolution From Space.
- Sir Fred Hoyle and Chandra Wickramasinghe assert that the chances of life’s springing from some ancient random mixing of chemicals are so “outrageously small” as to be absurd “even if the whole universe consisted of organic soup.”