Electrophoresis is a technique used to separate, identify and purify different substances in a mixture e.g. proteins.

A buffer solution has two key roles in electrophoresis:

1. It provides ions to carry the electric current. This allows charged molecules such as amino acids to migrate through the gel. Without ions, no current could flow.
2. It resists changes in pH. This is crucial because the charge on molecules depends on pH. If pH changed during electrophoresis, the migration of amino acids would be affected.

The size of the protein - smaller proteins migrate faster through the gel matrix than larger proteins.

A condensation reaction.

This reaction results in the elimination of a small molecule, in this case, water.

Polypeptides are long chains of amino acids.

When polypeptides contain more than 50 amino acids they are known as proteins.

A dipeptide is a molecule that results from the reaction of two amino acids.

The acidic -COOH group in one amino acid react with the basic -NH₂ group in another, as shown below. Three amino acids comine to form a tripeptide.