2.  Enzymes are made up of proteins.  Enzymes act as a catalyst in living organisms.  A catalyst is a substance that speeds up chemical reactions.  SO, enzymes speed up chemical reactions that occur in living organisms.

3.  The name of different enzymes always ends in –ase.  For example,  Maltase is an enzyme that breaks down the sugar maltose.  Lactase is an enzyme that breaks down the sugar lactose.  Sucrase is the enzyme that breaks down table sugar, sucrose, into fructose and glucose.

4.  All enzymes have an active site.  The active site is where the substrate attaches to the enzyme.  The substrate is the substance that the enzyme is going to process.

5.  Chemical reactions consist of reactants and products.  Reactants change or react to form something new called products.  With an enzyme, the reactants (or substrate) are converted into products, but the process happens in less time.

6.  The substrate (or reactants) attach to the active site to become an enzyme-substrate complex.  The enzyme-substrate complex undergoes a chemical reaction to create new products.  The products are then released from the active site.

7.  All reactions require energy to be carried out.  The minimum amount of energy required to start a reaction is called the activation energy.  Enzymes speed up a chemical reaction by lowering the minimum amount of activation energy needed to carry out a chemical reaction.

8.  In the diagram, the red line is the minimum energy needed for the reaction to occur without an enzyme.  The green line is the minimum energy needed for the reaction to occur with an enzyme.  The minimum amount of activation energy needed to get the reaction started is less with an enzyme present.

9.  Enzymes complete very, very specific jobs.  They can only work with specific molecules and only do specific tasks.  Enzymes are often referred to as a “lock and key” model:  One key fits one lock.  One substrate fits one enzyme.

10.  Enzymes are very specific, but they can be reused many times.  Once an enzyme has taken a substrate and converted it into new products, it can take in another substrate and convert it into new products as well.  An enzyme is reusable and can perform many reactions!

11.  Enzymes function best in certain conditions.  The 4 conditions that affect enzyme activity: 1. Substrate Concentration 2. Enzyme Concentration 3. Temperature 4. pH

12.  If there isn’t enough substrate (or reactants) present, then the enzyme cannot perform a chemical reaction.  In this diagram, 2 substrates are needed for the enzyme to work, but only 1 substrate is present, thus the reaction cannot happen.

13.  Alternatively, if there isn’t enough enzyme present, then the substrates have nothing to bind onto and the chemical reaction cannot occur.  In this diagram, 2 substrates are available for the enzyme to work, but there isn’t an enzyme present, thus the reaction cannot happen.  The substrates have to wait until an enzyme becomes available.

14.  Some enzymes become destroyed if they do not have the most “optimum” or ideal conditions to work.  Extreme temperatures destroy or denature enzymes.  Too HOT can denature an enzyme.  Too COLD can denature an enzyme.  Each enzyme has an optimum or best temperature for itself, but all enzymes are destroyed at HOT and COLD extreme temperatures.

15.  Each enzyme also has a pH value that it works the best in.  Some enzymes prefer acidic conditions (0-6).  Some enzymes prefer basic conditions (8-14).  Some enzymes prefer neutral pH conditions (7).  For example, Pepsin a stomach enzyme, prefers an acidic pH level to optimally carry out reactions. This would make sense, since the stomach is a very acidic environment.

16.  Enzymes are regulated, otherwise, they would just keep performing chemical reactions whether they were needed or not.  Enzymes are regulated in 3 ways: 1. Competitive Inhibition 2. Noncompetitive Inhibition 3. Feedback Inhibition  Inhibition means to prevent or stop.

17.  Competitive inhibition regulates enzymes.  Another molecule that is similar in shape, competes for the enzyme’s active site.  This other molecule becomes a block of the active site for the normal substrate.  The normal substrate can no longer bind onto the active site and thus the reaction cannot occur.

18.  Noncompetitive inhibition also regulates enzymes.  Another molecule, called an inhibitor, binds to another site on the enzyme, called an allosteric site. This causes the enzyme to change the shape of its active site, so that the substrate can no longer bind on to the active site and carry out a reaction.

19.  Feedback inhibition is another way that enzyme activity is regulated.  The end product made by the enzyme or enzymes, feeds back to the beginning and turns the enzyme off so that it stops making more product.