Agenda
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Collect Pre-lab #6
Lab Quiz #5
Paper Assignment due
Preview your Informal Lab Report for next
week
• No Microworlds available from this lab.
• Yet, you may use pond water, the microworld
slides, and maybe others?
Enzymes
Enzyme Reactions
ENZYME
SUBSTRATE
PRODUCT
Enzyme Reaction Rate
• Effect of enzyme concentration on reaction
rate
Enzyme Reaction Rate
• Effect of substrate concentration on reaction
rate
Enzyme Reaction Rate
• Effect of pH on reaction rate
Enzyme Reaction Rate
• Effect of temperature on reaction rate
Catecholase (Catechol oxidase)
Catechol + O2
Benzoquinone + H2O
Catecholase
(from Potato Extract)
Lab manual left off the water!
Catecholase
• Present in plants (potatoes)
• Reaction seen when potatoes or apples turn
brown
Exercise 1 – Effect of enzyme concentration on
Reaction Rate
• We will use the Color chart method
• A Color change = what?
1. Look at the set-up of the experiment. Answer
questions about the experimental design.
2. Set up the experiment as directed in the manual.
The reaction begins once catecholase and catechol
are together.
3. Watch reactions for 5 minutes, inverting to mix every
minute.
4. Record the color of each tube after each minute.
5. Understand that potato extract is dark to begin w/
because it has both catechol & catecholase!
Exercise 1 – Effect of enzyme
concentration on Reaction Rate
• THINGS TO NOTE:
– Catechol is toxic (don’t drink it; wash hands)
– Catechol waste goes in the bucket
– Keep potato extract on ice
– Be accurate!! poison
– Be quick & work together!
Part 2: Designing an Experiment
• Design an experiment to test one of the
following using catecholase:
– pH buffers (on counter, do not use pH 11!)
– Temperatures (water baths in the back)
– Different substrates
(sugars and starch)
– Salt concentration
(on counter)
In a recent experiment, I discovered that if allowed,
boys will eat ice cream until they become sick!
Part 2: Designing an Experiment
• Things to think about:
– What will your control group be?
– # of trials (replication)?
– Volumes of different solutions?
– Timing of reactions / when you measure color?
Designing an Experiment And Writing a Lab
Report
• You will also design an experiment next week and
write an informal lab report on the experiment next
week.
• This Informal LAB REPORT due in 3 weeks but please
get started now.
• Look at the format and example of a lab report in
Appendix A of lab manual
• Look at How to Write a Scientific Paper in Appendix A
of lab manual
Writing an Informal Lab Report
• To help you write an informal lab report, you will do
the “Paper Assignment”, see the link on the main lab
web page.
• In the Paper Assignment, you will read the scientific
paper found in the appendix of your lab manual and
answer the questions from the Paper Assignment
link.
• The Paper Assignment is due in 1 week.