 Proteins have many different functions in the body  Structure – proteins help provide structure and support, make up muscles and bones

 Transport – some proteins help to carry things around the body or into and out of cells

 Hormones – messenger proteins that carry signals throughout your body  Enzymes – proteins that help with chemical reactions  Antibodies – proteins that help protect the body from infection

 Proteins can have up to 4 levels of organization ◦ Primary ◦ Secondary ◦ Tertiary ◦ Quaternary

 Primary protein organization = the initial chain of amino acids  Peptide bond – the bond between amino acids to form the long chain we call a protein

 Secondary structure consists of two shapes ◦ Alpha helix ◦ Beta sheets  Caused by hydrogen bonding

 Three dimensional structure of a single protein molecule  Caused by hydrophobic interactions

 3D structure with multiple protein subunits  Held together by disulfide bonds

 Some proteins help to control reactions and cell processes  Enzyme – Specific proteins that can speed up reactions

 Energy can be either released or absorbed whenever chemical bonds form or are broken  Living things carry out chemical reactions that require energy  Organisms need a source of energy ◦ Plants have the sun ◦ Animals eat food

 Activation energy – the energy needed to start a chemical reaction

 Remember!  Some reactions give off energy…and some absorb energy!

 Chemical reactions that release energy often occur spontaneously  Chemical reactions that absorb energy won’t happen without an input of energy

 Draw two energy reaction graphs in your notes!

 Catalyst –a substance that speeds up the rate of a reaction  Catalysts lower activation energy  Enzymes are biological catalysts! They help speed up chemical reactions in your body!

 Enzymes are very specific!  A single enzyme usually only works with one type of reaction  HINT: The name of an enzyme usually has something to do with reaction it works with  Enzymes almost always end with –ase!!!

 Each enzyme will combine with only a specific molecule  Substrate – the molecule an enzyme binds to in a reaction  We call this the “lock and key model”

 Like a key in a lock…each enzyme fits only one substrate molecule

 Enzymes are picky…they only like to work under certain conditions  Each enzyme is designed to work in a certain temperature range  Enzymes in your body work best at 37 ºC

 pH also plays a role on enzyme activity  Enzymes in your stomach work best at a pH of around 2  Each enzyme works best at a specific pH level ◦ Most around 7.4 …Why?

 What type of molecule are enzymes?  Proteins  Proteins are made up of what type of molecules?  Amino acids

 The amino acids that make up proteins and enzymes are held together by which type of bond?  Peptide bond

 How do enzymes help speed up a chemical reaction?  Lower the reactions activation energy  What are two things that can change how well an enzyme works?  Temperature and pH

 Each enzyme works on one particular substrate  “Lock and Key Model”

 Enzymes aren’t used up!  Once the reaction is done, the enzyme is left unchanged and can continue its job  So enzymes are reusable!

 pH and Temperature have an effect on enzyme activity  Denature – when a protein loses its shape and can no longer work  mations/content/proteinstructure.html mations/content/proteinstructure.html