CH3 Nutrition

• Nutrients


  • carbohydrates
  • lipids
  • proteins
• Carbohydrate sub-types


  • monosaccharides
  • disaccharides
  • polysaccharides
• Protein sub-types


  • polypeptides
  • amino acids
• Lipid sub-types


  • fatty acids
  • glycerol
• Monosaccharides


  • glucose
  • galactose
  • fructose
• Disaccharides


  • maltose
  • lactose
  • sucrose
• Polysaccharides


  • starch
  • glycogen
  • cellulose
• Benedict's Test


  Detects reducing sugars
• Benedict's Test


  1. Add 2 ml of Benedict's solution to crushed / 2 ml of sample

  2. Shake vigorously

  3. Heat mixture in boiling water bath for 5 min
• Biuret Test


  Detects proteins
• Biuret Test


  1. Add 2 ml of biuret reagent to crushed / 2 ml of sample

  2. Shake vigorously
• Iodine Test


  Detects starch
• Iodine Test


  Add 2 drops of iodine solution to crushed / 2 ml of sample
• Ethanol Emulsion Test


  Detects lipids
• Ethanol Emulsion Test


  1. Add 2 ml of ethanol to crushed food sample

  2. Shake vigorously

  3. Decant supernatant into test tube containing 2 ml of distilled water
• Carbohydrates


  • C, H, and O with ratio of H:O=2:1
• Proteins


  • C, H, O, and N
• Lipids


  • C, H, and O
• Carbohydrates, lipids, and proteins are the 3 main classes of nutrients
• Non-reducing sugars


  • sucrose
• Cellulose


  Plant cell wall synthesis
• Starch


  Storage form of excess glucose, hence reserve store of energy
• Glycogen


  Storage form of excess glucose, hence reserve store of energy
• Glucose


  Converted into glucose and used as substrate for respiration to release energy for cellular processes; hence immediate source of energy
• Sucrose


  Glucose is converted into sucrose to be translocated from the leaves to other parts of the plant via the phloem
• Structural proteins


  Growth and repair of cells; contribute to the shaping and structure of molecules, cells, and tissues in the body
• Enzyme proteins


  Speed up rate of biochemical reactions by lowering the activation energy of the reaction
• Transport proteins


  Transmembrane proteins that control the movement of substances across the cell membrane
• Hormone proteins


  Chemical substance produced by an endocrine gland and secreted in minute quantities directly into the blood stream; transported by the bloodstream to one or more specific target organs, where the hormone exerts its effect; eventually destroyed in the liver
• Hormone lipids


  e.g. oestrogen, progesterone, testosterone
• Phospholipids


  Main component of cell membranes
• Subcutaneous fat


  Insulates against excessive heat loss
• Visceral fat


  Mechanical protection of internal organs and long-term storage of energy
• Water is a solvent
• Water is the main component of the cytoplasm and the matrix of various organelles in the cell. Water dissolves substances and allows biochemical reactions to occur in solution.
• Water is the main component of the contents of vacuoles and functions to store dissolved nutrients and mineral salts.
• Water is the medium of transport for dissolved substances in the blood, xylem, and phloem.
• Water is a reactant in hydrolysis reactions in digestion.
• Water is required as a raw material in the light-dependent stage of photosynthesis.
• Water maintains turgidity in plant cells that provides support for herbaceous plants.