CHEMICAL REACTIONS!!!!

reactant + reactant  product reactant  product + product reactant + reactant  product + product What are some other ways that we see chemical reactions represented?

 Energy is released or absorbed whenever chemical bonds form or are broken.  Chemical reactions that release energy often occur spontaneously, but chemical reactions that absorb energy will not occur without a source of energy.  The energy needed to start a reaction is called activation energy.

 Some chemical reactions require an activation energy that is too high to make it practical for living tissue.  These chemical reactions are made possible by enzymes.

Energy released Energy absorbed Reactants Products Time What do we start with in a chemical reaction? What do we end with in a chemical reaction?

Energy released Energy absorbed Activation energy reactant Products Time

Energy absorbed Energy released Reactant Products Activation energy Time What was the effect of having an enzyme present for the reaction?

Energy absorbed Energy released Reactant Products Which line would represent a reaction without an enzyme present? With an enzyme present?

A type of protein that speeds up chemical reactions by lowering the activation energy.

 Enzymes are very specific, usually catalyzing only one type of reaction.  Therefore, enzymes are named by the reaction they speed up.

 Enzymes provide a site where reactants can be brought together to react.  The reactants are known as substrates.  The substrate binds to a site on the enzyme called the active site.  They fit together like a lock and key.

 The enzyme and substrate bond together by intermolecular forces until the reaction is done.  Once the reaction is complete, the product is released from the enzyme and the enzyme is free to start the process again!  The enzyme is not used up in the process.

 Enzymes work like a lock and key.  Specific enzymes work with a specific chemical reaction.  We call the reactants of that reaction substrates. enzyme substrate (reactant)

 The substrate binds to an active site on the enzyme. Only a certain substrate fits into the active site!

When the substrates bind, the chemical reaction occurs, and the product is released. What happens to the enzyme? The enzyme remains unchanged & ready for the next set of substrates.

Enzymes work most efficiently within a certain range of temperature and pH!  Temperatures outside the range can change the shape  A pH value outside the range will cause the enzyme to change shape and be less efficient WHY?

denatured.  When an enzyme loses its shape it is said to be denatured.