Biomolecules

    Cards (100)

    • Condensation reaction
      Reaction occurs between hyrodxyl groups and produces one molecule of water. A bond forms between both molecules known as a glycosidic bond.
    • Hydrolysis reaction

      Reaction that occurs when a molecule is split into two smaller molecules with the addition of water
    • Monosaccharides
      Single sugar molecules,
      Glucose, galactose, fructose
      Glucose C6H1206= hexose sugar
    • Properties of monosaccharides
      Soluble in water due to many hydroxyl groups
      Hydrophilic- dissolves in water
    • Disaccharides
      Formed when two monosaccharides chemically bond via a condensation reaction.
      Maltose, sucrose, lactose
    • Disaccharide word equations
      Glucose + glucose -> maltose
      Glucose + fructose -> sucrose
      Glucose + galactose -> lactose
    • Polysaccharides
      Carbohydrates that are made up of more than two monosaccharides such as starch, glycogen and cellulose.
    • Carbohydrates
      Polysaccharides, made up of many monosaccharides, joined together through a condensation reaction.
    • Starch
      A storage polysaccharide in plants consisting entirely of alpha glucose.
      Comes in two forms; amylose and amylopectin.
    • Amylose
      Simplest, unbranded form of starch, has 1-4 glycosidic bonds only.
      Twists into a compact helix with bonds forming between glucose molecules. Makes it excellent for storage.
    • Amylopectin
      Has 1-4 and 1-6 glycosidic bonds so it coiled but also has branches.
      Increases the area for enzymes to hydrolyse it so can be broken down quicker into a-glucose than amylose.
    • Properties of starch
      Insoluble, does not affective osmosis (will not lower water potential)
      Too large so cannot diffuse out of cells.
    • Glycogen
      Storage form of glucose in animals.
      Highly branched so has a larger surface area.
      Glycogen, due to a higher number of accessible ends, is more readily hydrolysed into glucose
    • Why do animals require glycogen?
      They require glycogen to be hydrolysed into glucose quicker than plants can hydrolyse starch because animals have higher metabolic rates.
    • Glycogen is insoluble so..

      Does not affect water potential or diffuse out of cell
    • Cellulose structure

      Beta glucose molecules join together by condensation reactions to form long straight chains.
    • Chains of cellulose are..
      Joined together in layers, and the chains are held together by formation of hydrogen bonds
    • Microfibrils
      formed by 30-40 strands of cellulose with H bonds; very high tensile strength it's almost crystalline
    • Cellulose fibre
      Microfibrils form hydrogen bonds between other Microfibrils and together form a cellulose fibre.
    • Benedict's test for reducing sugar
      1.Add Benedict's solution to sample and heat to 95 degrees C.
      2. Coloured precipitate indicates reducing sugar.
      Blue= no reducing sugar
      Green= little sugar
      Yellow= some sugar
    • Benedict's test for non-reducing sugars

      No change in colour so...
      3. Boil with hydrochloric acid to hydrolyse glycosidic bonds.
      4. Neutralise solution by adding small amounts of solid sodium hydrogen carbonate.
      5. Test as before using Benedict's reagent and it should give positive result.
    • Starch test
      Add two drops of iodine solution and positive result turns blue-black.
    • Lipids
      Triglycerides and phospholipids are two types of lipids.
    • Triglyceride
      Made from one molecule of glycerol linked to 3 fatty acid molecules.
      3 condensation reactions, forming 3 water moelcules, forming 3 ester bonds.
      Add a fatty acid release a water molecule.
    • Properties of triglycerides
      -energy storage molecules (tails contain lots of chemical energy)
      -insoluble in water (water potential unaffected)
      Hydrophobic/non-polar
      Slow conductor of heat.
      Protection - surrounds organs
    • Condensation of triglyceride
      Glycerol + 3x fatty acid ——> triglyceride + 3 H20
    • Hydrolysis of triglyceride
      Triglyceride + 3 H2O broken down by lipase to 3x fatty acid and glycerol
    • Fatty acids
      Carboxyl group (COOH)
      R group, which is a hydrocarbon chain that can vary in length.
    • Saturated fatty acid

      Do not have any double bonds between carbon atoms
    • Unsaturated fatty acids
      Contain one or more double bonds between carbon atoms.
    • Phospholipid
      One glycerol, one phosphate group, two fatty acid molecules.
      2 condensation reactions, forming 2 H20 molecules, forming 2 ester bonds.
    • How does phospholipid bilayer form
      Phosphate group has a negative charge (polar), fatty acid tails have no charge (non-polar)
      This makes phospho-glycerol head hydrophilic and the fatty acid tails hydrophobic (not soluble)
    • Phospholipid bilayer
      Hydrophobic fatty acid tails are arranged in middle away from water. Hydrophilic heads arranged on outside in contact with water.
      POLAR as each component behaves differently.
    • Properties of phospholipids
      Hydrophobic fatty acid chains
      Hydrophilic phosphate group
    • Emulsion test for lipid
      - A small amount of the sample is placed in a test tube with 2cm3 of ethanol
      - The mixture is shaken so that the fat dissolves. If the sample is solid, then it must be crushed or ground with ethanol
      - Water is then added drop by drop and shaken again
      - A white emulsion (layer) of fat droplets should be visible if fat is present
    • Triglycerides + phospholipids
      Glycerol
      Ester bonds
      Unsaturated or saturated fatty acids
      Insoluble in water
      Carbon, hydrogen and oxygen but phospholipids also contain phosphate.
    • Differences between trig and phospho
      3 and 2 fatty acids
      Triglycerides are hydrophobic but phospholipids have hydrophobic and hydrophilic region.
      Phospholipids form a layer on surface but triglycerides don't.
    • Globular proteins

      Enzymes
      Transport proteins - such as Haemoglobin which transports oxygen
      Signal proteins- carry messages around blood such as insulin
      Contractile proteins- actin and myosin, involved in muscle contraction
      Defensive proteins, such as antibodies
    • Structural proteins
      Keratin - nails and hooves
      Collagen - tendons
    • Elements in proteins
      All proteins and amino acids contain N,C,H, O. Some contain S as well.