Proteins and Enzymes

• amino acids are monomers that proteins are made out of
• peptide bonds are formed when an condensation reaction takes place between two amino acids
• dipeptides are formed by the condensation of two amino acids
• polypeptides are formed by the condensation of many amino acids
• what are the four different components of amino acids?

  1. Amine group 2. Carboxyl group 3. carbon containing side chain or R group 4. Hydrogen atom
• what are the four levels of proteins?

  primary, secondary, tertiary and quaternary
• the primary structure is many amino acid monomers join together by condensation reactions to form a polypeptide chain
• the secondary structure is formed when hydrogen bonds form between the amino group and the carboxylic acid group which forms a helix
• the tertiary structure is formed by interactions between the R groups of amino acids which results in the helices to be twisted and folded further into more complex 3D structures
• in the tertiary structure what are the bonds that form between the r groups?

  hydrogen, ionic and disulphide
• the Quaternary structure is formed when more than one polypeptide chains are combined together
• what is the definition of an enzyme?

  a globular protein that speeds up the rate of reaction by lowering the activation energy of a reaction it catalyzes
• what are the 2 types of enzymes?


  • intracellular enzymes (never leave the cell)
  • extracellular enzymes (secrete out of the cell)
• an enzyme is a tertiary protein structure with a 3D shape
• Lock and key model?

  substrate and enzyme active sight are complimentary and fit perfectly
• induced fit model?

  active sight is similar to substrate but not complimentary and when substrate binds to enzyme the active sight changes shape so that it becomes complimentary to the substrate
• what are the 2 factors that affect the rate of reaction?

  • Change in shape of the active sight - pH, temp, non-competitive inhibitors
  • change in number of collisions between substrate and active sight - substrate concentration, temp, competitive inhibitors