Test for the presence of protein (LC 2026) (Leaving Cert Biology): Revision Notes

Test for the presence of protein

Background:

Proteins are a group of biomolecules made up of subunits called amino acids. There are 20 basic amino acids that form all proteins. Examples of proteins in living organisms include enzymes, hormones, antibodies, and keratin (found in hair and nails).

Materials needed:

• Food sample
• Distilled water (control)
• Biuret solution
• Test tubes

Method:

1. Add food sample to a test tube. Place distilled water in another test tube (control).
2. Add biuret solution.
3. Record colour change.
4. Repeat for control sample which is distilled water.

Result:

A positive result for the presence of a protein is blue to purple.

Control remains blue.