Name:____________________________________________Date: _______

Analyzing Graphics: Enzymes

1.  Enzymes act on substrates.  Label the enzyme, substrate, active site, and products on diagram.

enzyme substrate graphic

Answer true or false to the following statements based on the graphic:

a.  _______  Enzymes interact with  many different  substrates.

b.  _______  Enzymes change shape after a reaction occurs.

c.  _______  An enzyme can be reused with a new substrate.

d.  _______ The substrate is changed in the reaction.

e.  _______  If the shape of the enzyme changed, it would no longer work.

f.   _______  When all substrates are used, the reaction stops.

2.  Enzymes speed up the reaction by lowering the activation energy needed for the reaction to start. Compare the activation energy with and without the enzyme.

enzyme energy graph

Identify the part of the graph that shows:

a) ___ Overall energy released during reaction

b) ___ Activation energy with enzyme

c) ___ Activation energy without enzyme

3. Enzymes work best at optimal temperature and pH values.   For example, the enzyme, pepsin, in your stomach must be able to function in a highly acidic environment to break peptide bonds found in proteins.

Acidic or basic conditions can disrupt the hydrogen bonds between the loops of the protein chains.  If this disruption occurs near the active site, the enzyme can become distorted and not fit the substrate perfectly.  The rate of reaction is reduced as more enzymes become denatured.

optimal graph

a) What is the optimal pH for pepsin? _______                  For lipase? _______

b) Do you think lipase  is an enzyme that is found in the stomach? Why or why not?


4.  Enzymes can be  inhibited.   Inhibitors can slow down or stop enzymatic reactions.   There are two types of inhibition:  competitive and allosteric.

enzyme inhibition

Answer true or false to the following statements based on the graphic:

a) _____  Increasing the number of inhibitors will decrease  the overall  rate of reaction.

b) _____  Allosteric inhibitors block  the active site.

c)  _____  Allosteric inhibitors change the shape of the enzyme.

d)  _____  Adding a competitive inhibitor will increase the number of products in the reaction. 

e)  _____ Competitive inhibitors bind to the substrates.