Biological Molecules

🧪 Carbohydrates

Carbohydrates are made of carbon, hydrogen, and oxygen. They are the primary energy source in living organisms.

• Monosaccharides — simple sugars (glucose, fructose, galactose); general formula (CH₂O)ₙ
• Disaccharides — two monosaccharides joined by glycosidic bond (e.g. maltose = glucose + glucose; sucrose = glucose + fructose)
• Polysaccharides — many sugar units; starch (energy storage in plants), glycogen (energy storage in animals), cellulose (structural in plant cell walls)
• Joined by condensation reactions (release water); broken apart by hydrolysis (add water)

🧪 Proteins and Lipids

• Proteins — polymers of amino acids joined by peptide bonds; folded into specific 3D shapes; roles include enzymes, antibodies, structural proteins, transport (haemoglobin)
• Lipids (fats/oils) — glycerol + 3 fatty acid chains (triglyceride); long-term energy store, insulation, cell membrane component
• DNA — double helix; made of nucleotides; stores genetic information
• ATP — energy currency of cells; adenosine triphosphate