Biology 1.4 - Proteins

• What does the sequence of amino acids control?

  The shape and function of proteins
• What are the 5 types of proteins?

  Structural, hormones, antibodies, receptors, enzymes(S.H.E.A.R)
• What is the role of structural proteins?

  To hold tissues together
• Define hormones.

  Chemical messengers which carry a message from a gland to a receptor via the blood.
• What are antibodies?


  Proteins made by white blood cells, which destroy pathogens by binding to them. (pathogen = An organism causing disease to its host.)
• Define receptors.


  Bind to a hormone and tell the target cell what to do.
• Describe a biological catalyst.

  Speeds up chemical reactions in cells and remain unchanged in the process
• Define an active site

  Where the substrate fits into the enzyme and is a complementary shape to it.
• Define a product


  The molecule(s) made by an enzyme-controlled reaction.
• Define optimum conditions

  The temperature and pH which the enzymes are most active.
• What is denatured?

  When the active site changes shape, the substrate no longer fits, and this affects the rate of the reaction.
• Define a substrate

  The reactant(s) in a reaction, and is specific to an enzyme.
• How does temperature affect enzymes' rate of reaction?

  As temperature increases ,the rate of reaction increases until after the optimum is reached when rate of reaction rapidly decreases to zero
• Why do enzymes stop working past their optimum temperature?

  Enzyme is denatured (substrate can no longer bind to active site)
• Why do enzymes not work well at lower temperatures?

  There is not enough kinetic energy for the substrate to collide and bind to active site
• How does a change in pH affect enzyme structure?

  pH change affects the bonds holding enzyme structure together, causing it to denature.
• what are proteins joined together by?

  Polypeptides, strong chemical links