Protein Formation (A-level Biology)

Protein Formation

Peptide Bonding

Proteins are formed when amino acids become linked to each other via peptide bonds.

  • Condensation reactions join amino acids. Condensation reactions lead to formation of strong covalent bonds, called peptide bonds, which hold the amino acids together. Water is also released during the reaction.
  • Condensation reactions can form dipeptides or polypeptides.
      • Two amino acids linked to each other are known as a dipeptide.
      • Several amino acids linked together are known as a polypeptide.
  • Proteins consist of one or more polypeptides.
  • Peptide bonds can be broken down by hydrolysis reactions. This can break proteins and peptides down to their constituent amino acids.
  • There are 20 common amino acids present in living organisms. The only difference between them is the R side group.
  • Glycine is the smallest amino acid. In glycine the R group is just a hydrogen atom.

There is no need to memorise the amino acids below, but use Figure 1 to understand the ways in which amino acids can differ.

A-level Biology - Protein Formation
A-level Biology – Protein Formation

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