Summary
Biological molecules are organic compounds essential for life, composed mainly of carbon, hydrogen, and oxygen, with some containing nitrogen, phosphorus, and sulfur. They provide energy, raw materials for growth, and participate in metabolism through hydrolysis and condensation reactions.
- Carbohydrates — long chains of simple sugars called monosaccharides. Example: Starch, glycogen, and cellulose are polysaccharides.
- Proteins — long chains of amino acids with a specific sequence determining their structure and function. Example: Enzymes and antibodies.
- Fats — lipids that are solid at room temperature, composed of glycerol and fatty acids. Example: Triglycerides.
- DNA — a double helical molecule made of nucleotides, responsible for genetic inheritance. Example: Chromosomes in cells.
Exam Tips
Key Definitions to Remember
- Carbohydrates are made of monosaccharides.
- Proteins are made of amino acids.
- Fats are made of glycerol and fatty acids.
- DNA is made of nucleotides.
Common Confusions
- Confusing the tests for different biomolecules.
- Misunderstanding the role of water as a solvent.
Typical Exam Questions
- What is the test for starch? Use iodine solution; a blue-black color indicates starch.
- How do you test for proteins? Use the biuret test; a violet color indicates proteins.
- What is the structure of DNA? DNA is a double helix with nucleotide bases pairing A-T and C-G.
What Examiners Usually Test
- Understanding of the structure and function of biological molecules.
- Ability to describe and perform food tests for biomolecules.
- Knowledge of the role of water as a solvent in biological systems.