Are molecules composed of amino acids all proteins?

Molecules formed by linking amino acids are mostly referred to as proteins, but not all amino acid polymers are considered proteins. Specifically:

1. Proteins: These are complex molecules formed by the folding of one or more polypeptide chains (chains of amino acids), usually with specific functions and structures. Proteins are typically composed of 20 standard amino acids and require a specific three-dimensional structure.

2. Polypeptides: These are shorter chains of amino acids, usually fewer than 50 amino acids. Polypeptides can be components of proteins but do not necessarily have complete functions.

3. Amino acid polymers: Any molecule formed by amino acids linked through peptide bonds is theoretically a polypeptide or protein, but the integrity of specific functions and structures determines whether it is referred to as a 'protein.'

Therefore, while all proteins are composed of amino acids, not all molecules formed by linking amino acids are proteins.

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