Proteins are made from smaller subunits called amino acids, which are linked together in long chains.

Core idea

  • Proteins are composed of many amino acids joined end-to-end in a specific sequence.
  • The bond that connects one amino acid to the next is called a peptide bond, so a chain of amino acids is also called a polypeptide.

Quick Scoop

  • Each amino acid has the same basic backbone but a different side group, so changing the order of amino acids changes the protein’s shape and function.
  • One long polypeptide chain can fold into a single protein, or several folded chains (called subunits) can assemble into a larger multi-subunit protein complex.

In simple exam language

  • “Proteins are made up of amino acid units held together by peptide bonds” is the standard textbook answer.

TL;DR: Proteins are made from amino acid subunits joined in chains by peptide bonds, which then fold and sometimes assemble into multi-subunit protein complexes.

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