Bio

• Biological molecule


  A chemical compound found in living organisms
• Elements found in biological molecules

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
  • Sulfur (S)
  • Phosphorus (P)
• Biomolecules have a wide range of sizes and structures and perform a vast array of functions
• Four major types of biomolecules

  • Carbohydrates
  • Lipids
  • Nucleic acids (DNA / RNA)
  • Proteins
• Chemical elements found in all biological molecules

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
• Polymer


  Made from monomers
• Monomer


  Smaller units from which larger molecules are made
• Four types of polymers

  • Polysaccharide (carbohydrates)
  • Lipid (fat and oil)
  • Polypeptide (protein)
  • Deoxyribonucleic acid (DNA)
• Polysaccharide


  Polymer of monosaccharides
• One molecule of carbohydrate contains about twice as many hydrogen atoms as carbon or oxygen atoms
• Ratio of C:H:O in carbohydrates = 1:2:1
• Organic molecules


  Food & living tissues
• Sugars


  • Glucose [C6H12O6], fructose and sucrose
• Polysaccharides


  • Starch, cellulose, glycogen
• Monosaccharide


  One sugar unit (monomer)
• Disaccharide


  Two monosaccharides
• Polysaccharide


  Many monosaccharides combined
• Starch, glycogen and cellulose are polymers of glucose
• Polysaccharides are large, complex, insoluble and not sweet-tasting molecules
• Polysaccharide = polymer
• Sources of carbohydrates


  • Jam, sweets, table sugar (sucrose), fruits, cool drinks, pancakes, syrup
  • Potatoes, French fries, maize, pasta, wheat, bread, mahango, macaroni, spaghetti, oatmeal, and rice
• Glucose


  • Main source of energy for cells - respiration
  • Building blocks for larger carbohydrate molecules (starch, glycogen, cellulose)
  • The form in which carbohydrates are transported in blood, around the body
• Glycogen


  • Energy storage in animal tissue (main storage form of glucose)
  • Stored in liver and muscles
• Advantages of storing glycogen rather than glucose

  • Compact molecule
  • Large quantities can be stored
  • Insoluble in water = no osmotic effect
  • Can easily be hydrolised to glucose
• Starch


  • Energy source and an energy storage in plants
  • Main storage form of glucose in the plant
• Advantages of storing starch rather than glucose

  • Starch is insoluble and has no osmotic effect
  • Starch can also easily be hydrolised into glucose
  • Cannot move out of cells
• Cellulose


  • Main material for production of plant cell walls
  • Cell walls support plant cells and prevent bursting
• Humans cannot digest cellulose, but it is necessary to prevent constipation and it may help to prevent colon cancer
• Lipids (fats and oils)

  • Monomers = three fatty acids & glycerol
  • Not water soluble - dissolve in alcohol and ether
• Animal fats (butter and lard)

  • Saturated fatty acids
  • Higher melting points
  • Solids at room temperature
• Plant fats (sunflower and olive oils)


  • Unsaturated fatty acids
  • Lower melting
  • Liquids at room temperature
• Lipids have a chemical elements ratio of carbon (C), hydrogen (H) and oxygen (O) greater than 2:1
• Lipids


  Two structural components: glycerol and three fatty acids
• Sources of lipids


  • Plant seeds (sunflower oil, olive oil, peanut oil)
  • Plant sources: avocado, margarine and peanuts
  • Animal sources: Eggs, cheese, fat meat, butter, lard (pig fat), oily fish and milk
• Roles of lipids in living organisms

  • Energy source
  • Energy storage
  • Insulating layer against heat loss
  • Poor conductor of heat (blubber)
  • Structural component of cell membranes (phospholipids)
  • Formation of myelin sheath – nerve cells
  • Protection of vital organs (kidneys / heart)
  • Birds spread oil over feathers = repel water
  • Insects - waxy layer = prevent water loss (evaporation)
  • Waterproof cuticle on leaves = reduce water loss (evaporation)
• Polypeptides /protein


  Monomers = amino acids
• Chemical elements in proteins

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
  • Phosphorus (P)
  • Sulphur (S)
  • Iron (Fe)
• Amino acids


  Monomers of proteins
• Proteins


  Polymers made up of monomers called amino acids
• There are 20 different amino acids