Test 2 study

• When fewer calories are taken in than are expended


  Fuel is taken out of storage deposits & oxidized (digested)
• Breakdown (digest) glycogen


  From liver & muscle cells
• If there is a ongoing imbalance of intake/output of calories, malnutrition can occur, including underweight, overweight and obesity
• Carbohydrates


  Molecules containing carbon, hydrogen, and oxygen atoms
• Carbohydrates (CHOs) range in size and complexity

  • Polysaccharides, e.g., cellulose
  • Oligosaccharides, e.g., maltodextrin
  • Disaccharides, e.g., sucrose and lactose
  • Monosaccharides, e.g., glucose and fructose
• Monosaccharides


  General structure is C6H12O6
• Carbohydrates


  • Main human energy source
  • Provide between 45-65% total food energy intake
  • Help control blood glucose and insulin metabolism
  • Participate in cholesterol and triglyceride metabolism
  • Energy storage
• Extra glucose in the bloodstream is stored as glycogen


  1. In the liver and muscle tissue until further energy is needed

  2. Excess glucose that can't be stored as glycogen is then turned into fat through lipogenesis (using acetyl CoA, usually from glycolysis)
• Simple Carbohydrates


  • Mono and disaccharides (also called sugars)
  • Easily utilized for energy- cause rapid rise in blood sugar (High GI- glycaemic index)
• Simple Carbohydrates


  • fructose
  • lactose
  • sucrose
  • glucose
• Simple Carbohydrates are found in lollies, fruit juice, sugar and honey
• Fructose is the main ingredient in High Fructose Corn Syrup (not common in Aus), often blamed for increase in obesity
• Complex Carbohydrates


  • Oligo and polysaccharides
  • Take longer to digest and have slow effect on blood sugar (Low GI)
• Complex Carbohydrates


  • cellulose
  • amylose
• Complex Carbohydrates are found in apples, lentils, brown rice, whole grains
• Other Carbohydrates


  • Starches
  • Fibre
• Starches


  • Complex CHOs with a lot of glucose
  • Found in potatoes, pasta and wheat
• Fibre


  • Non-digestible complex CHO with a lot of cellulose and pectin
  • Insoluble: Good for healthy bacterial growth in colon and help with defecation. Found in bran, seeds, vegetables.
  • Soluble: helps decrease blood cholesterol. Found in oats, broccoli, dried beans.
• Proteins


  • Linear polymers built of monomer units called amino acids
  • The function of a protein is dependent on its individual structure, determined by the sequence of 20 possible amino acids
  • They contain C, H, O, N and often S, P
• Proteins


  • Provide between 15-25% total food energy intake
  • Catalysts (enzymes)
  • Transport and store other molecules such as oxygen (carrier and channel proteins)
  • Generate movement (actin and myosin in muscle)
  • Transmit nerve impulses (Na+ channel)
  • Control growth and differentiation (hormones)
• Lipids


  • A group of compounds usually insoluble in water
  • Foods sources are edible oils and fats
  • Lipids contain C, H, and small amounts of oxygen
  • Made up of glycerol and fatty acids
  • Can be saturated, unsaturated or trans fats (depends on saturation of C-C bonds with H)
  • High and low density lipids
  • Triacylglycerols make up 95% of dietary lipids
• Lipids


  • Serving as energy storage (fats/oils)
  • Provide 20-35% of total dietary energy
  • Constituents of membranes (cholesterol, phospholipids)
  • Hormones (steroids)
  • Vitamins A, D, E and K (fat soluble)
  • Oxygen/ electron carriers (heme)
• Vitamins


  • Provide no energy but are essential for proper functioning of the body, as are minerals
  • They are organic substances (containing carbon) with important roles in metabolism such as co-enzymes or co-factors
• Vitamins


  • A: retinol production (eyesight)
  • C: protein metabolism
  • D: required for calcium absorption
  • E: antioxidant
  • K: required for blood clotting
  • B: 8 different vitamins, needed in energy metabolism
• Vitamin deficiencies can cause scurvy, rickets, blindness, and anemia
• Minerals


  • Inorganic substances (don't contain carbon)
  • Required in diet in very small amounts
  • Roles in biological processes include providing strength in bones, oxygen transport, and thyroid activity
• Minerals


  • Calcium- found in milk and yoghurt, salmon
  • Iron- found in red meat, green leafy vegetables
  • Iodine- found in seafoods, iodised salt
• Mineral deficiencies can cause osteoporosis, goiter, and iron deficiency anaemia
• Enzymes


  • Proteins
  • Biological catalysts
  • Reduce the energy required to start a reaction
  • Speed up reactions in the body
  • Essential to sustain life
• Enzymes


  • Each enzyme is involved in a specific reaction
  • It assists in the building or breaking of molecules
  • These molecules are called substrates
  • Therefore, each enzyme has a specific substrate
• Enzymes


  • The enzyme lactase breaks down lactose
• Most enzymes end in "-ase"
• What enzymes do


  • Speed up the breakdown of one substrate into multiple products
  • Speed up the process for turning multiple substrates into one product
• Enzymes


  • Work to their full capacity at their optimum temperature and pH
  • The optimum factors for an enzyme depend on the environment where it is required
• High temperature or altered pH can permanently change the active site, causing the enzyme to become denatured
• Low temperature will inactivate the enzyme – in this state it won't work to its full capacity, but it can be changed back
• These reactions would occur with or without enzymes, but the enzyme places the substrate in the right position for the reaction and lowers the activation energy, allowing the reaction to occur more quickly
• Factors affecting the rate of an enzymatic reaction

  • pH
  • Temperature
  • Enzyme concentration
  • Substrate concentration
  • Inhibition
• Enzymes work best in temperatures that they are found, e.g. the human body at 37°C
• Effect of temperature on enzyme activity

  • Increase in temp = increase in activity
  • Increase in activity = increase in collisions between substrate and enzyme → faster rate of reaction
  • If temperature is too high, bonds break and the protein loses its functional shape (becoming permanently denatured)
  • The enzyme can no longer bind with the active site of the substrate
  • Enzymes are not denatured at low temperatures