Name:
Date:
Homework: Enzymes and Optimum Conditions
Directions: read the information below. All the KEY vocabulary is bold/underlined for you. Use this
for the BACK questions!
Enzymes Can Become Denatured
Enzymes are proteins that increase the rate of chemical reactions in a cell. Enzymes are required
for all chemical reactions in a cell. The shape/structure of an enzyme is very important, because its
shape helps it do its job in a reaction as a maker or breaker. If the shape of an enzyme’s active
site changes, the enzyme can no longer fit the substrate it was meant for. This means the enzyme
can no longer make or break what it is supposed to. When this happens, the enzyme becomes
denatured, which means it stops working. An enzyme’s ability to keep the same shape depends on
two conditions: temperature and pH. It is important for cells to maintain optimum conditions in
order to prevent their enzymes from denaturing. Optimum conditions means the environmental
conditions are at the ideal or best for an enzyme to work its fastest.
Temperature and Enzymes
As the temperature in cells increases (gets hotter), the
speed at which the enzyme works ALSO increases. If the
temperature gets too high/hot, the enzyme denatures, and
stops working.
Temperature and enzyme activity
Decreased or low/cold temperatures cause the speed of an
enzyme to slow down. The lower/colder it gets, the slower the
enzyme and substrates move. That’s why it is VERY important
for cells to maintain a constant temperature!
The blue line shows the optimum
temperature for most enzymes is
37ºC, or human body temperature
(98.6 oF).
pH levels and enzymes
Changes in pH levels also cause an enzyme to denature. Different enzymes work best at different
pH levels. The optimum (best) pH for an enzyme depends on where it normally works.
pH and enzyme activity
The black line shows most enzymes have an optimum pH of about 7- 8.
Name:
Directions: Use the reading to complete ALL of the questions.
Date:
Vocabulary Directions: Use the reading to fill-in the definitions for each term below.
enzyme: ___________________________________________________________________
__________________________________________________________________________
denatured: _________________________________________________________________
__________________________________________________________________________
Optimum conditions: __________________________________________________________
__________________________________________________________________________
Directions: Use the information from the reading to answer the questions below. Make sure to
read the graphs & the captions!
1. What type of macromolecule are enzymes? ________________________
2. Identify one reason why enzymes are important for cells. __________________________
_______________________________________________________________________
_______________________________________________________________________
3. Why is the shape of an enzyme important? _______________________________________
_____________________________________________________________________
4. Explain why an enzyme stops working once it is denatured.
5. Identify two conditions that cause an enzyme to denature.
6. Explain why enzymes don’t work very fast at low temperatures:
7. What is the OPTIMUM TEMPERATURE for enzymes? ____________________
8. What is the optimum pH for enzymes? ____________________