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What do moths eat with that long proboscis?

But if you ate a moth (eww), okay maybe if a bat ate a moth, what kind of nutrition would it get?

People say, “you are what you eat,” but is that literally true?

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Phenomenon

All organisms need to make and break molecules

Making: organisms need molecules that they don’t get in their diet.
Breaking: organisms need to get rid of molecules that might be harmful, eliminate waste, and break down molecules to access their energy

Example: hydrogen peroxide (H₂O₂) is made in all of our cells (it is a byproduct of metabolism). It causes oxidation which damages our cells. Therefore, we need to break it down to prevent that harm.

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Enzymes

Essential Question:

How do organisms make and break molecules?

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Every line represents an enzyme that converts one molecule (dot) to the connecting molecule (dot). The middle circle on the bottom is how we convert stored energy in sugars to useable energy (ATP) - respiration!

So how does the moth convert nectar (sugar) into protein?

Task: find the two parts of the chart on the left that would need to be connected via a metabolic pathway

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Additional Resource

Watch this video and complete this Handout for extra practice

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Pair Share

What monomers make up proteins?

How might those monomers interact with each other? (Hint: look at the ways that individual atoms interact)

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What are enzymes?

Proteins
Job: act as catalysts to speed up reactions inside cells
Not permanently changed or used up as the reaction occurs (they are re-used!)
Twisted and folded into a 3-D shape

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What are enzymes?

specific for the reaction(s) they catalyze
Often have names that often end in -ase

lactase (breaks down lactose)
maltase (breaks down maltose)
polymerase (builds nucleic acids)
amylase (breaks down starch)

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Pair Share

Which requires you to put in more energy?

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How do enzymes work?

They strain chemical bonds, lowering the activation energy required for a reaction to move forward
Less energy needed helps a reaction move forward more quickly (speeds it up)

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How do enzymes work?

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Free

Energy

Progress of the reaction

Reactants

Products

Free energy of activation

Without Enzyme

With Enzyme

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Pair Share

What might limit an enzyme from doing its job?

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Pair Share

Why can’t you unlock your neighbor’s door with your key?

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Enzyme - Substrate Complex

An enzyme acts on a substance (reactant) called a substrate.
The substrate binds to a location on the enzyme called the active site - they fit together like puzzle pieces.

Enzyme

Substrate

joins

Active Site

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Active Site - Lock and Key Mechanism

The fit is so precise that the active site and substrates are often compared to a lock and key.

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Denaturation

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Functioning Active Site

Substrate

Enzyme

Denatured Active Site

Substrate

Enzyme

If the shape of the enzyme is changed, the substrate no longer fits into the active site as well. Eventually, the active site becomes so deformed that the substrate does not fit at all and all activity stops.

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Catalase

An example enzyme, found in all cells.

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Check your understanding

Use the video on slide 6 and slides 7-18 to review the following:

What is an enzyme?
How does it work?
What does it work on?
Why can it only work on specific substance(s)?
What are some common examples?

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Let’s reconnect to Baby Matthew!

Now that you know something about enzymes, think-pair-share with your neighbor:

What new questions do you have about Baby Matthew’s situation?

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Enzyme Lab

Essential Question:

How do organisms make and break molecules?

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Enzyme Lab Student Template

Make a copy of the Enzyme Lab Student Template or get a copy from your teacher.

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When we’ve finished this experiment, you should be able to say…

I can identify the patterns that represent enzyme activity at different temperatures, pH, enzyme concentrations and substrate concentrations and use this to make a prediction for optimal enzyme activity.

Content Objective

I can represent these patterns graphically, mathematically, visually, and with words.

Language Objective

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By the end of class, you should be able to say…

Learning Objective

I can describe evidence about patterns to support claims about biomolecules

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Catalase Enzyme

This enzyme breaks down hydrogen peroxide (H₂O₂)into water (H₂O) and oxygen gas (O₂).

All living cells contain and need catalase...

...because hydrogen peroxide, which is a byproduct of cell metabolism, can kill cells.

2H₂O₂(liq) → 2H₂O (liq) + O₂(gas)

hydrogen peroxide → water + oxygen

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How can we measure catalase activity?

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Investigating Catalase Enzyme Activity

Wild Guess Question: What are the best

to maximize catalase’s activity in a potato?

How tall a bubble column would be made in a test tube under these conditions in 2 minutes?

Guess Based on Observation

Inquiry to Determine Pattern

Making Sense of the Pattern Through Consensus

Data Informed Prediction

temperature (°C),	catalase concentration (%), and
pH (0-14),	hydrogen peroxide concentration (%)

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To identify how these four variables affect the activity of catalase enzyme, we will form four sets of research groups. Each will perform an experiment with a different independent variable:

Temperature
Enzyme Concentration
Substrate Concentration
pH

Investigating Catalase Enzyme Activity

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Research Questions

What is the effect of

-temperature
-pH
-substrate concentration
-enzyme concentration

on the activity of ________, as measured by ________?

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Null Hypothesis:

in words “_________ does not affect __________.”

Enzyme Activity-Height of O₂ Foam (cm)

Your Parameter

(Temp, Concentration, pH)

Investigating Catalase Enzyme Activity

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Hypothesis:

sketch in graph form (think about one set-up, then think doubling or halving your parameter)
in words “I think the (your parameter) affects enzyme activity in a ______ relationship because ____________________________.”

Enzyme Activity-Height of O₂ Foam (cm)

Your Parameter

(Temp, Concentration, pH)

Investigating Catalase Enzyme Activity

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Variables and Controls

Group Investigation:

My group is investigating _(insert variable name here)_

Variables:

Our independent variable is __________________ and our dependent variable is ______________________.

Controls (with values where appropriate): _________

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Methods Summary

Detailed directions will be distributed to each group. Read through your procedure with your group and write a summary on your lab report and draw a picture.

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Teacher Notes:

Best way to prepare catalase from potatoes is with a juicer. Use Yukon Gold or Red potatoes. Slice in half and then juice with a juicer. Dilute juice with 1x or 2x the volume of distilled water (test 2ml of the diluted catalase with 5ml dH2O and 5 ml store-bought 3% Hydrogen Peroxide in advance to make sure that your test tubes don’t overflow with foam in 4 minutes. If the tubes overflow then use the 2:1 dilution instead of 1:1). Works best if you juice before each class period.

Alternatively you can blend one medium sized potato with 300 ml of water; you do need to strain this mix with cheesecloth, fine mesh strainer or coffee filters to collect potato juice (catalase solution). This is dilute enough to use directly. You will need to recalculate the Catalase concentration column on the slide with the variables in a table if you use this method.

2016 addendum: we found that a 1:1 ratio of DI to juice caused a lot of test tubes to overflow. We had better results with a 2:1 ratio of DI to juice.

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Important Reminders

Before You Begin

1. Add test tubes with hydrogen peroxide to test tubes with catalase QUICKLY and start your timer after the first tube!

2. After the reaction time, take a picture (make sure you can see the ruler!) to measure your foam.

3. Leave pipets in their containers-don’t mix!

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Run Your Experiment

Collect Your Data

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Test Tube	Temp (°C) (± 2)	pH (± 1)	H₂O₂ Conc. in tube (± 0.2%)	Potato Juice Conc. in tube (± 1%)	Height of Foam (cm) (± 0.2)
none	N/A	N/A	0	0	0
A			0.5%	8.3%
B			1.0%	16.7%
C			1.5%	25.0%
D			2.0%	33.3%
E			2.5%	41.7%

Investigating Catalase Enzyme Activity

Percentages are final concentrations of each component in test tubes

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Pointers About Graphs

Desmos Template (linked in student template)

You may encounter a new mathematical pattern, so you may have to choose unfamiliar options for your best fit line!
Need help with Desmos?

Watch Desmos Tutorial video or
Read the Desmos Graphing How-To

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Graphs of Good Data

Checklist

Should have:

Title with variable being investigated
Axis labels with units
Reasonable error bars
Best fit line(s)/curve
Equation (for linear / proportional graphs only)

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Notes about your Equation

Once you have graphed, WRITE DOWN YOUR EQUATION
(you can also screenshot the best fit line info from Desmos)
Use the IV and DV from your experiment!
Example: y = ax + b a=.03 b=0

So: y = 0.03x or

foam height = 0.03(enzyme concentration)

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Examples of Good Graphs

Effect of Catalase Concentration on Catalase Activity

activity = 0.031 cm of foam ⨉ (catalase concentration)

range: 0% catalase to 100% catalase

For every % of catalase, 0.031 cm of foam was generated

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Examples of Good Graphs

Effect of H₂O₂ Concentration on Catalase Activity

activity = 1.18 cm of foam

when H₂O₂ concentration ≥ 1.34%

height of foam = 0.89 ⨉ (H₂O₂ concentration)

when 0 < H₂O₂ concentration < 1.33%

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Examples of Good Graphs

Effect of pH on Catalase Activity

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Examples of Good Graphs

Effect of Temperature on Catalase Activity

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Use the Slide Sharing Template made for you by your teacher for your class

Put Your Graph in the Shared Slides

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Include on your slide:

Name(s)
Independent variable with ranges
Name of function observed in data
Optimum value for your variable
Equation using the variables of the investigation (linear and horizontal only)
For Normal Distribution: report the values of the a, b, c, d variables
Ranges for each equation (if more than one equation fits your data)
Desmos graph (with labeled axes including units and uncertainties)

Live link to Desmos graph

Put Your Graph in the Shared Slides

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Quality Control of Data and Graph
Orienting to the Data
Finding Similarities & Differences
Find Pattern

--- Walk the Triangle ---

Make Sense of Pattern

in light of differences

Predicting the Future

Big Ideas to Consider for our Data Discussion

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Making Sense of Our Data

The analysis of your data needs to be shared by several group members:

Identify what variable your group tested, and the range of the variable you manipulated (smallest to largest).
Let us know what kind of pattern you observed in your data and what it means.
Explain the conclusion you can draw from your data--how is enzyme activity affected by your variable?

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Organize/ Pair share about similarities in the graphs that studied the same variable
What would happen if we doubled the amount of enzyme? quadrupled?
For proportional graphs, what does the slope mean?
What about the horizontal lines?
Apply the PopBeadase analogy to this chemical reaction.

Board Meeting Questions

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Writing the Lab Conclusion

Resources to use:

Conclusion template in your lab document

Resource Sheet for writing lab conclusions

Graphic Organizer for writing lab conclusions

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Conclusion:

Claim: _____(IV) and _____(DV) have a ______ relationship.
Evidence: How do you know this? Reference your data explicitly with points, trends, shape, equation or other evidence.

Model: If you have an equation that you can make sense of, state your equation in words.
Use the shape of your graph

Reasoning: What scientific explanation can you give for WHY these results make sense?

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Conclusion:

Justify your results:

Explain why you got the pattern you did in terms of substrate and enzyme interactions (you might need to reference concentrations, reaction rates, and/or enzyme shape (lock and key model)

Summarize class data:

State the optimum conditions for catalase activity for all four variables (based on class data).

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Returning to the Wild Guess

Now that you know what the ideal pH, temperature, and concentration of catalase and hydrogen peroxide are, what would the height of the bubbles be if you used all these parameters to optimize catalase activity?

Make a prediction of height of foam if you were to test catalase activity in its optimal conditions.

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The Power of Patterns�& �Determining Confidence in a Prediction

Think-Pair-Share:

What are some factors that impact the confidence we can have in our prediction?

State how confident in you are in that prediction and your reasoning why (see next slide). (Consider all of the graphs that you saw in your class data analysis)

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Determining Confidence in a Prediction
Considerations	Prediction is within testing range of all groups	Prediction is near the testing range of all groups	Prediction is far from the testing range of all groups
All groups’ best-fit lines hit through the center of all the data points	High	Medium-High	Medium
All groups’ best-fit lines hit near the center of many data points	Medium-High	Medium	Medium-Low
All groups’ best-fit lines do not hit many data points	Low	Very Low	Extremely Low

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Identify Limitations

What other things must we consider that may affect your confidence?

Think of:

reasons why the data might not be completely precise or accurate, such as:

procedural problems in the experimental set-up, or
known errors in measurement, or

something else you are still uncertain about.

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Identify Limitations

What other things must we consider that may affect your confidence?

Use your knowledge of the procedure and our ability to control the experiment to explain how these limitations could have affected your results.

(You cannot use “human error” as a limitation! Be specific!)

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Test Evidence-Based Prediction

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Test Evidence-Based Prediction

Science works!

We can find a pattern in nature and use it to accurately predict the future.

Wild guesses are sometimes close, sometimes not. How do you know which of these it is?

With careful investigation we can predict the future and understand the past– with some level of confidence.

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Test Evidence-Based Prediction

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Compare Prediction to Actual Result

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Now that you have some experience and knowledge with enzymes, what further testable question(s) could you investigate?

-OR-

What is a connection you can make between what you learned in this investigation to everyday life?

Extension / Application of Knowledge

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