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!!
– 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)
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
• LAB REPORT rough draft due next week
• 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
• See the Lab Report Peer Review sheet on my web
site for how it will be graded
Writing a Lab Report
• TYPED
• 12 point font, double spaced
• TITLE
– Should tell what will be in the lab report
– Good format is “The effect of the independent
variable on the dependent variable”
Writing a Lab Report
• INTRODUCTION
– Background information about your experiment
• General background someone would need to understand the
topic
• Specific background someone would need to understand your
experiment
• Important vocabulary
– Very brief summary of your experiment
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Question you’re addressing
State hypothesis
Explain why the hypothesis is worth investigating
Make predictions about results
• 3-5 paragraphs
Writing a Lab Report
• MATERIALS and METHODS (Procedure)
– Detailed description of what you did so that someone
else can replicate your experiment
– Discuss your experimental design
• State the independent and dependent variable
• Identify control, constants, replication
– Use the passive past tense (“the solution was heated”
not “we heated the solution”)
– Write using paragraphs
– Be specific (measurements, units, etc)
• About 2-3 paragraphs
Writing a Lab Report
• RESULTS
– Even if it doesn’t support your hypothesis, it’s still a
result!
– Present ALL data in an organized, meaningful form
(quantitative, qualitative).
– Data in table(s), Graph(s), or Figure(s) (pictures)
– A paragraph that presents DATA and does NOT explain
why you observed the results.
• 1 paragraph of text plus a table, graph, or etc.
Writing a Lab Report
• DISCUSSION (& Conclusions)
– Summarize your problem & hypothesis (review it).
– Summarize your data by discussing specific data in
sentences. (Summarize, no raw data.)
– Discuss what your results mean.
– Discuss the importance of your results and how it ties
in with what you wrote in the introduction.
– Discuss how your results answer (or do not answer)
your original question
– Is your hypothesis supported by this data or not?
Writing a Lab Report
• DISCUSSION (& Conclusions)
– IF YOUR HYPOTHESIS WAS SUPPORTED:
• Evaluate possible explanations for the results based on
the information in your introduction.
• Answer your question.
• Explain things that could be improved in your
experiment and what were possible errors.
• Discuss future studies that would add to your results.
Writing a Lab Report
• DISCUSSION (& Conclusions)
– IF YOUR HYPOTHESIS WAS NOT SUPPORTED:
• Evaluate possible explanations for the results based on
any experimental errors OR personal misconceptions /
lack of background information.
• If your experiment didn’t work due to errors, you CAN
NOT answer original question.
• Explain things that could be improved in your
experimental design and how you could correct any
errors.
• Discuss future studies that would add to your results.
Writing a Lab Report
References (lab manual calls it Literature Cited)
• See info in Appendix A
–At least THREE references:
• At least ONE peer-reviewed journal article from a
scientific publication
• Not including your lab manual (although you can
reference this for one of the two other references)
• Anything from wikipedia or the web do not count &
MUST be confirmed with an additional source!
What to turn in
• ROUGH DRAFT due next week
– Bring Three copies of your rough draft
– Make three copies of the Peer Review Grading
Sheet and staple a copy to each copy of the rough
draft.
– Deduction if this is not done as both are needed
by your peer reviewer.
• NEXT WEEK: Rough drafts will be distributed
randomly for you to peer edit