Biological Molecules

• Monomers


  the smaller subunits from which larger molecules are made
• Polymers


  molecules made from lots of repeating units (monomers) joined together
• Saturated


  Don't have any double bonds between carbon atoms, have the largest number of hydrogens it can have
• Unsaturated


  has one or more double bonds between carbon atoms, causing the chain to bend
• Hydrophobic


  repel water (e.g. fatty acid chains, makes lipids insoluble in water)
• Phospholipid


  A glycerol molecule, a phosphate group and 2 fatty acid chains
• Hydrophilic 


  attracts water (e.g. phosphate group/head of a phospholipid)
• Micell


  only one layer of phosphate, transports fat soluble substances
• Bilayer phosphates


  2 layers, transports water soluble substances
• Monosaturated 


  a single double bond present
• Polysaturated


  More than one double bond present
• R group (amino acid)


  variable group, can contain other elements including sulphur generally containing carbon
• Amine group (amino acid)


  H2N
• Carboxyl group (amino acid)


  COOH
• Primary structure of a protein


  sequence of amino acids in a polypeptide chain, determines 3D shape or tertiary structure
• Secondary structure of a protein


  hydrogen bonds form between the amino acids in the chain these make the alpha-helix and beta-pleated sheet structures stable
• Tertiary structure of a protein


  3D shape of the polypeptide chain, it is a specific shape due to the sequence of amino acids and the hydrogen bonds, ionic bonds and disulphide bridges that form between the R groups
• Quaternary structure of a protein


  proteins are made of more than one polypeptide, non-protein groups many also be associated
• Lock and Key model


  substrate will only fit active site of a specific enzyme, substrate has a complimentary shape to active site, suggesting enzyme is rigid
• Induced Fit model


  enzymes change shape slightly to fit substrate, enzyme is flexible, enzyme puts strain on the substrate, distorting bonds, lowering the activation energy
• Competitive Inhibitor 


  has similar shape to the substrate molecules, compete with the substrate to bind to the active site of the enzyme, block the active site, so substrates cannot bind, so no ES complexes are formed
• Non-competitive Inhibitors


  Don't bind to the active site, as they have different shape to the substrate so don't compete, bind to the allosteric site, causes the active site of the enzyme to change shape so it is no longer complimentary to the substrate so no ES complexes can be formed