Carbohydrates • all made from carbon (C), hydrogen (H), and oxygen (O) and rich in energy • monosaccharide - simple sugars, reducing properties (i.e., donate electrons), e.g., glucose • disaccharides – 2 monosaccharides joined together, e.g., maltose and sucrose • polysaccharides - many monosaccharides joined together (e.g., glycogen, energy storage compound in animals, starch in plants) • main source of energy Copy table p.37- carbohydrate identification (add notes if needed)
Lipids Made from C, H, and O. They are a diverse group including the following : 1. Simple lipids (triglycerides)
2. Phospholipids
3. Steroids
Roles of lipids 1. As an energy store. Fats have double the amount of energy of the same mass of carbohydrate. Excessive glucose is stored as fat. To release energy fats are broken down as follows (copy or refer yourself to fig. 5.9 p.39): Glucose All pink Glycerol 3 C sugar arrows are Fat Fatty acids
Pyruvic acid acetyl CoA Krebs cycle
reversible => excess stored as fat.
2. As an insulator. Thermal insulation as a layer of fat under skin, and nerve insulator as a layer of fat wrapped around nerve fibres. 3. Fat pads on the soles of feet and palm of hands.
4. Transport of vitamins
5. Hormones. Sex hormones are steroids.
6. Phospholipid bilayer in cell membrane.
Proteins • made from C, H, O, and nitrogen (N) • composed from amino acids • excess amino acids cannot be stored • amino acids undergo deamination making urea and organic acids (compounds from Krebs cycle) • organic acids enter Krebs cycle • tissue protein (including skeletal muscle) only used during prolonged starvation.
Marathon Running
1st few mins – glucose from muscle glycogen 30 mins – blood glucose (from liver glycogen) and slow-acting fatty acids Later stages – fatty acids as glucose decreases More carbohydrates eaten before the race, the less fat needed. More detail, including diagram, on p.41