Agenda Collect Prelab 5 Lab Quiz 4 LAB

Agenda • Collect Pre-lab #5 • Lab Quiz #4

LAB 5: 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 p. H on reaction rate

Enzyme Reaction Rate • Effect of temperature on reaction rate

Catecholase Catechol + O 2 Colorless Benzoquinone Catecholase (Potato Extract) Brown

Catecholase • Present in plants (potatoes) • Reaction seen when potatoes or apples turn brown

Exercise 1 – Effect of enzyme concentration on Reaction Rate • Color chart method • Color change = what? 1. Look at the set-up of the experiment. Answer questions about experimental design. 2. Set up the experiment using the procedures on the back and the Table on the front. 3. Watch reactions for 5 minutes, inverting to mix every minute. 4. Record the color of each tube after each minute (different from procedures)

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!!

Part 2: Designing an Experiment • Design an experiment to test one of the following using catecholase: – p. H buffers (counter) – Temperatures (Water baths) – Different substrates (Sugars and starch) – Salt concentration (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?

Part 3: Designing an Experiment • LAB REPORT #1 due next week • Look at the format at the end of the lab manual

How to Write a Scientific Paper • See Appendix B in lab manual • Look at peer review sheet 15

Writing a Lab Report • TYPED • 12 point font • May be single or double spaced

Writing a Lab Report • 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 • • 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, does NOT explain why you observed those results. • 1 paragraph plus table, graph, etc

Writing a Lab Report • DISCUSSION (Conclusions) – Summarize your problem and hypothesis (review) – Summarize your data by discussing specific data in sentences – Discuss how your results answer (or do not answer) your original question – How do your results fit with what you know? – Importance of results – Is your hypothesis supported by this data or not? – Did you confirm your predictions?

Writing a Lab Report • DISCUSSION (Conclusions) – IF YOUR HYPOTHESIS WAS SUPPORTED: • Evaluate possible explanations for the results based on background information. • Answer the original question. • Explain things that could be improved in your experiment • Discuss additional experiments 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 or how you could correct errors • Discuss additional experiments that would add to your results.

Writing a Lab Report • CITATIONS – Refer to info in Appendix B – At least THREE sources: • At least ONE peer-reviewed journal (check with library) • Not including your lab manual (although you can ref this) • Anything from wikipedia or the web MUST be confirmed with another 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 rubric and staple one copy of rough draft to one copy of grading rubric. – 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

Using the Spec • Read your samples – Prepare samples containing water, catechol and potato extract – Re-blank spec – Read absorbance for each sample

Part 2: Catecholase • Measuring color change with spectrophotometer – measures the amount of light that penetrates at different wavelengths

Product Formation Part 2: Product Formation and Absorbance

Using the Spec • Zero the spec – Mix 1 m. L potato extract + 5 m. L d. H 2 O in tube – Invert tube to mix and wipe clean so the spec can read it appropriately. – Follow the directions for using the spec (each may differ). You will need to zero it. – When the spec is ready, insert the tube (mark it so you insert it the same way every time) – Make sure the spec readings make sense; if something is off the readings are garbage