Biomolecules

• Glycolysis occurs in the cytoplasm and produces a small amount of ATP from glucose degradation.
• Covalent bonding - Atoms share a pair of electrons in their outer shells.

  Ionic bonding – Ions (charged molecules) with opposite charges attract each other.

  Hydrogen bonding - The uneven distribution of charges causes polarity, and this causes weak electrostatic attractions to occur between adjacent molecules.
• Monomers – Molecules joined together in units.

  Polymers - Multiple monomers in a long chain.
• Polymerisation - The process of bonding between monomers
• Condensation – Monomers joining together.

  Hydrolysis – Monomers separating.

  Both processes lead to water being released.
• Metabolism – All reactions taking place within an organism.
• Carbohydrates

  o   Made up of Carbon, Hydrogen and Oxygen.

  o   Obtained through diet in food like pasta, rice, or sugars.

  o   Carbon atoms easily form bonds with other carbon atoms, enabling large molecules made of carbon chains to build up. These carbon chain molecules form organic molecules found in living organisms.
• In carbohydrates, the basic monomer is sugar.

  Monosaccharides - Single sugars, sweet tasting, soluble, contain 3-7 carbon atoms, eg, glucose, galactose and fructose

  Disaccharides – Two sugars, eg sucrose, maltose and lactose

  Polysaccharides – Many sugars
• Polysaccharide - Many sugars joined by condensation reaction. Eg, starch (amylase) and glycogen (animal storage polysaccharide).
• Disaccharide - Two sugars joined by condensation reaction (glycosidic linkage). Eg, sucrose (glucose + fructose), lactose (galactose + glucose) and maltose (two glucoses)
• Starch - Polysaccharide used as energy store in plants. Found in seeds, tubers and grains. It can be broken down into simple sugars during digestion.
• Glycogen - Animal storage polysaccharide. Used when there are no carbs available from diet. Stored in liver and muscle cells. Can be broken down into simple sugars during digestion.
• Sugars are used as energy source by cells. They can be stored as polymers such as starch and glycogen when there is excess energy available. When energy levels drop, these stores can be broken down into simple sugars which can then be oxidised to release energy.
• Starch is a polymer of amylose and amylopectin. Amylose has linear structure while amylopectin has branched structure. Starch is insoluble in water but swells on contact with it. It is also tasteless and odourless.
• Glycogen is similar to starch but contains more branches per unit length than amylopectin. Glycogen is highly branched so that it forms a compact globular shape. This allows many glucose units to fit into one cell. The branching points allow rapid breakdown of glycogen to glucose during periods of high activity.
• Glycogen - Animal storage polysaccharide. Used when there are no carbs available from diet. Stored in liver and muscle cells. Can be broken down into glucose during digestion.
• Cellulose - Plant cell wall material. Not digested by humans so not absorbed. Provides structure and support to plant cells.
• Chitin - Structural component of exoskeletons of insects and crustaceans. Also present in fungi cell walls.
• Sucrose - Disaccharide formed between glucose and fructose. Common table sugar. Found in fruits and vegetables. Can be hydrolysed back into its two component monosaccharides.
• Fructose - Monosaccharide which is sweeter than sucrose or glucose. Found in fruit, honey and some root vegetables. Absorbed directly into bloodstream via intestinal epithelial cells.
• Maltose - Disaccharide formed between two glucose molecules. Produced during the breakdown of starch.
• Lactose - Disaccharide found in milk. Formed between galactose and glucose. Hydrolysed by lactase enzyme.
• Amylopectin - Branched polymer made up of alpha-glucose units joined together with alpha glycosidic bonds. Formed during starch synthesis. Makes up about 80% of starch.
• Amylose - Linear polymer made up of alpha-glucose units joined together with alpha glycosidic bonds. Formed during starch synthesis. Makes up about 20% of starch.
• Glucose - Simple monosaccharide. Most common source of energy for living organisms. Present in all foods containing carbohydrates. Absorbed directly into bloodstream via intestinal epithelial cells.
• Galactose - Monosaccharide that forms part of lactose. Present in breast milk and other dairy products.