Enzyme Practice
Name: _____________________________Period:___
All enzymes have a certain shape that includes their active site. They need this shape so that they can fit their specific
substrate. If an enzyme’s shape changes, the substrate will no longer be able to bind to the enzyme and the enzyme will no
longer be able to speed up the reaction by lowering the activation energy.
Different environmental conditions can alter an enzyme’s shape. These conditions include:
1. Temperature. Enzymes usually work within a small range of temperatures, near the organism’s normal body
temperature. If the temperature is too hot or too cold, the enzyme will not maintain its shape.
2. Ionic conditions. Enzymes can stop functioning if they are exposed to inappropriate concentrations or types of salts.
3. pH. pH is how acidic or basic a substance is. Many enzymes function best at a nearly neutral pH. Some, however, such
as digestive enzymes in the stomach work best under acidic conditions. If the pH is too high or too low for the enzyme, it
will not maintain its shape.
Answer the following questions:
1. How are enzymes similar to a lock-and-key?
2. What happens if the shape of an enzyme is changed?
3. What 3 factors affect enzyme activity?
4. A certain enzyme functions best at 37 degrees Celsius. Explain what will happen if the temperature gets above 37
degrees. Explain what will happen if the temperature falls below 37 degrees.
5. Lactase is a digestive enzyme that breaks down milk sugar and is found in the
small intestine. Typical conditions in the small intestine are a pH of 7.5 and a
temperature of 37 degrees Celsius. An experiment is performed with lactase and
the conditions for the four trials are specified below. During which trial, do you think
lactase will work the best? List 2 reasons to justify your choice.
Trial #
1
2
3
4
Temperature
37 degrees Celcius
40 degrees Celcius
37 degrees Celcius
40 degrees Celcius
6. How might a fever (increased body temperature) affect enzymes in the body? Why might this be dangerous?
7. The human body maintains the pH of blood between 7.35 and 7.45. Why might this be necessary?
CHALLENGE QUESTION:
8. How does homeostasis relate to enzyme activity?
pH
7.5
7.5
7.0
7.0
RAFT Activity GUIDELINES
R = Role = Pretend you are an enzyme.
A = Audience = You are writing to your substrate.
F = Format = You must write in the form of a letter. (Dear ___________ substrate,….)
T = Topic = Enzyme activity as outlined below:
Grading Rubric:
For a “C” grade: Follow guidelines in the box below (1-6), use complete sentences, and draw a picture of the enzyme and
substrate on the back of your letter.
For a “B” grade: Do “C” grade work + draw a COLORED picture of the enzyme and substrate to go along with your letter
on unlined paper.
For an “A” grade: Do “B” grade work + volunteer to read your letter (with enthusiasm) to the class.
SUPER CREATIVITY is essential for the “A” grade.
Be sure to include the following in your letter:
1. State what enzymes do: Increase or decrease speed of reaction?
2. Increase or lower activation energy?
3. Include the terms substrates (reactants) and products.
4. What is the active site?
5. What does lock-and-key mean in terms of enzymes?
6. What affects enzyme activity? (Hint: pH and temperature – EXPLAIN the effect)
Brainstorm space:
Biology 2 – September 14, 2015
Use the projector to have students see the objective and catalyst (warm-up) for the day. I usually give students about 4
minutes to work through the question with their neighbors while I take attendance. After this time take volunteers or call on
individuals to respond to the question.
On Monday’s I usually go through the week – you can refer them to the week plan on the board and let them know I will
review it with them on Tuesday. Please point out the quiz on Friday.
After this show a short video on enzymes – they saw the Amoeba sisters one last week.
I like Enzymes – a fun introduction on youtube (username donttellteacher, 4:46 long)
Feel free to clarify/reiterate the key ideas on enzymes – this is new material for them (with the exception of the
teaser video and toothpickase lab last week)
After the basics, pass out the Enzyme Practice page. You can either have them go all the way through it and read the
example letter when you hand it out (probably best in period 2) or have them work on the front side and then check in and
give them more details on the second part (period 1).
They should write their letters on a separate piece of paper and attach them to the worksheet. If there is time you can have
some read them at the end of class. (Please write down those who volunteer). If there is not time I will have them share on
Tuesday.
Thank you so much for taking my classes, feel free to tell them why I am out, some know already.
Raewyn
Example Letter to Read Aloud for class.
Love Letter Example
Dear Sammy Substrate,
My name is Emilia the enzyme. I think you are gorgeous! I am going to tell you a little bit about myself so that maybe you
will become interested in attaching to my active site.
I am a FUN enzyme! I am a fast worker because as an enzyme I increase the speed of reactions. I am also down to
earth: I lower the activation energy that it takes to get chemical reactions going.
Sammy Substrate, I hope you will be the reactant for my chemical romance. The products we could make together would
be magnificent. You would be the perfect fit for me. Like a lock-and-key, we’re perfect for each other and no one else.
Just remember that you and I can only get together under very specific circumstances. It has to be the right time, we can’t
rush. I need the right pH and the right temperature before I would be willing to have you join my active site. It can’t be too
cold, but it can’t be too hot on the day you decide to get with me. And don’t be too acidic or basic! If you are either one of
those, I would lose my shape and you couldn’t attach to me =( So pick the right pH and temperature!
Enzyme kisses!
Emilia the Enzyme.