Bio molecules

• Carbohydrate


  A molecule that contains ONLY carbon, hydrogen and oxygen
• Monosaccharide

  Single carbohydrate unit (monomer)
• Disaccharide

  Two monosaccharide monomers bonded together
• Polysaccharide


  More than two monosaccharide monomers bonded together
• Polymer


  Many monomers bonded together
• Monomer


  Single units
• Hydrolysis reaction

  Reaction breaking a chemical bond between monomers using a water molecule
• Condensation reaction


  Reaction forming a chemical bond between monomers, removing a water molecule
• Starch

  • Made of amylose and amylopectin
  • Both made of alpha glucose with 1:4 glycosidic bonds
  • Amylopectin is branched, due to also having 1:6 glycosidic bonds
  • Amylose is coiled due to hydrogen bonds

  
• Cellulose

  • Beta glucose, in chains of 1:4 glycosidic bonds
  • Every alternate monomer is inverted
  • Many H bonds form between chains making it strong
  • Many cellulose chains together form microfibrils
• Glycogen

  • Highly branched chains of alpha glucose. More branched than amylopectin- more "ends" so faster hydrolysis for animals, that have a higher metabolic rate
• Similarities between cellulose and starch

  • Both made of glucose
  • Both contain H bonds
  • Both have 1:4 glycosidic bonds

  
• Differences between cellulose and starch

  • Cellulose is beta glucose whereas starch is alpha
  • Starch (amylose) is coiled, whereas cellulose is not
  • Starch (amylopectin) is branched whereas cellulose is not

  
• Test for reducing sugar

  1. Add benedicts and heat

  2. Goes from blue to brick red

  
• Test for non-reducing sugar


  1. Boil in acid, then neutralise

  2. Then add benedicts and heat

  3. Goes blue to brick red

  
• Test for starch

  1. Add iodine dissolved in potassium iodide

  2. Goes yellow to blue-black
• Starch and glycogen as storage molecules

  • Insoluble, so they don't affect water potential
  • Starch is coiled so it is compact
  • Branched, so easily hydrolysed

  
• Triglyceride

  A kind of lipid. One molecule of glycerol and three fatty acid chains

  
• Saturated fatty acid

  No double C=C bonds
• Unsaturated fatty acid


  Some double C=C bonds, causes the tail to "kink"
• Phospholipid


  Molecule where one fatty acid in a triglyceride is replaced with phosphate
• Test for lipid

  1. Emulsion test: shake sample with ETHANOL, then add water

  2. Milky white emulsion forms
• Primary structure

  The sequence of amino acids
• Secondary structure

  Hydrogen bonds form between amino acids in the primary structure chain, causing it to coil (alpha helix) or fold into beta pleated sheets
• Tertiary structure

  Ionic, hydrogen, disulphide bonds form between R groups of amino acids, causing further complex folding

  
• Quaternary structure

  More than one polypeptide chain interacts, by forming ionic, hydrogen or disulphide bonds

  
• Test for protein

  Add Biuret solution = turns from blue to purple

  
• Activation energy

  The energy that needs to be supplied to chemicals before a reaction can start
• How enzymes work

  • Biological catalyst - lowers the activation energy
  • The active site is complementary to the shape of the substrate
  • Substrate enters the active site
  • A perfect fit is induced
  • Strain is put on bonds
  • Product no longer fits so exits the active site
• Substrate

  The chemical being acted upon by an enzyme
• Active site

  The shape within an enzyme molecule where the substrate fits
• Induced fit model

  The active site changes shape in the right way to perfectly fit the substrate
• Denatured


  • Enzyme's active site changes shape because hydrogen or ionic bonds are broken
  • The substrate no longer fits - no more enzyme-substrate complexes
• Competitive inhibitor

  • Substance with a similar shape to the substrate, so it competes with the substrate for the enzyme's active site
• Non-competitive inhibitor

  • Substance that binds to an allosteric site of the enzyme, changing the shape of the active site so the substrate no longer fits
• As temperature increases up to optimum


  • Enzymes and substrate have more kinetic energy
  • More successful collisions - more enzyme substrate complexes form

  
• After optimum temperature

  • Hydrogen bonds break at high temperatures
  • Shape of active site changes
  • Substrate no longer fits - no more enzyme-substrate complexes form
• pH affects enzyme action

  • Acid contains H+ ions, alkali contains OH- ions
  • These break hydrogen and ionic bonds
  • Shape of active site changes so substrate no longer fits - no more enzyme-substrate complexes form
• Nucleotide

  Monomer of RNA and DNA
• Phosphodiester bond

  Bond that forms between phosphate group of one nucleotide and the sugar of another