c3

• Carbohydrates


  Biomolecules that provide calories and energy
• Simple sugars


  • Carbon
  • CH₂OH
  • H
  • OH
  • HICI
  • OH
  • Oxygen
  • C
  • Hydrogen
  • OH
  • CH₂OH
  • CH₂OH
  • BR
  • OH
  • CH-CH
  • OH
  • OH
• Complex carbohydrates


  • Long chains
• Carbohydrates provide calories and energy
• Monosaccharide


  One sugar saccharide
• Disaccharide


  Two sugar saccharides
• Oligosaccharide


  A few (3-9) sugar saccharides
• Polysaccharide


  Many (10 or more) sugar saccharides
• Glucose


  • Most important
  • One of the main sources of calories
  • Can cross blood-brain barrier
  • Nourishes the brain
• Fructose


  • Most important
  • One of the main sources of calories
  • Can cross blood-brain barrier
  • Commonly found in honey, fruits, & root vegetables
  • Nourishes the brain
• Galactose


  • One of the main sources of calories
  • Can cross blood-brain barrier
  • Milk sugar
• Lactose


  • Found in milk of mammals e.g. cow & breast milk
• Sucrose


  • Table sugar
  • Found in fruits & vegetables e.g. sugar cane & sugar beets
• Maltose


  • Found in molasses used to ferment beer
• Oligosaccharides


  • Galacto-oligosaccharide found in soybeans
• Polysaccharides


  • Most abundant carbohydrate in food
  • Starches - intestinal enzymes can break down, found in rice, potatoes, wheat & maize, not sweet
  • Dietary fibers - intestinal enzymes cannot break down, broken down a bit by bacteria in large intestine, beta-glucan good for heart health, passes through small intestine undigested, slows absorption of simple sugars, bulk matter in stool, maintain blood glucose
• Glycosidic bonding


  Bonding between sugar units, requires water (H2O) to form
• Glycosidic bonding in maltose

  1. 4-glycosidic bond, lined up
• Glycosidic bonding in lactose

  1. 4-glycosidic bond, stacked
• Glycosidic bonding in sucrose

  1. 2-glycosidic bond
• Carbohydrates are broken down by enzymes like amylases, lactase, sucrase, maltase
• Glucose absorption and utilization

  1. Enters bloodstream

  2. Pancreas releases insulin which moves glucose into all cells for energy and stimulates liver to promote fat & protein synthesis

  3. Stored as glycogen
• Hypoglycaemia (low blood sugar)


  Symptoms: weakness, fatigue, anxiety, dizziness, fast heartbeat, stomach pain, headache, irritability, blurry vision
• Hyperglycaemia (high blood sugar)


  Symptoms: need to urinate often, shakiness, irritability, very thirsty, hunger
• Healthy diet should include nutrient-rich foods like fruits, vegetables, dairy, and grains, with less than 10% added sugars
• Carbohydrate types


  • Simple sugars
  • Starches
  • Fibers
• Simple sugars


  Body can readily absorb
• Starches


  Take longer to absorb
• Fibers


  Can only partially absorb (with gut bacteria)