Overview
This topic covers the key biological molecules essential for life, including their definitions, functions, and relevance to IGCSE CIE Biology exams.
Biological Molecules in Living Organisms
- Living organisms are made of carbohydrates, proteins, lipids (fats and oils), and nucleic acids (DNA and RNA).
- Water is also a vital biological molecule contributing to most chemical reactions in cells.
Carbohydrates
- Carbohydrates provide energy and are made from carbon, hydrogen, and oxygen.
- Simple sugars (monosaccharides) like glucose join to form complex carbohydrates (polysaccharides) like starch and glycogen.
Proteins
- Proteins are made from amino acids linked by peptide bonds.
- Proteins are required for growth, repair, enzymes, hormones, and antibodies.
Lipids
- Lipids consist of fatty acids and glycerol.
- They serve as energy storage, insulation, and protection of organs.
Nucleic Acids
- DNA carries genetic information and is made up of nucleotides.
- RNA is involved in protein synthesis.
Importance of Water
- Water is a solvent for chemical reactions and helps transport substances in organisms.
- It maintains cell shape and temperature stability.
Key Terms & Definitions
- Carbohydrate — an energy-providing molecule made of carbon, hydrogen, and oxygen.
- Protein — a molecule made from amino acids essential for body structure and functioning.
- Lipid — a molecule composed of fatty acids and glycerol, used for energy storage and insulation.
- Nucleic Acid — a long molecule (DNA/RNA) that stores and transfers genetic information.
- Enzyme — a protein that speeds up chemical reactions in the body.
- Amino Acid — the building block of proteins.
- Monosaccharide — the simplest form of carbohydrate.
- Polysaccharide — a complex carbohydrate made of many sugar units.
- Peptide Bond — the bond connecting amino acids in proteins.
Action Items / Next Steps
- Review definitions and summary notes for Topic 4 Biological Molecules.
- Practice questions by topic, including multiple choice and structured questions.
- Complete any set homework or assigned reading for this topic.