Enzyme Lab DebriefAP Bio Periods 3-4

Kat Aliff, Melanie Arnold, Kate Hollern, Kiran Phuloria, & Kenna Poptic

2B: Obtaining the BaselineDiscuss general procedure:● Add Hydrogen peroxide (10 mL), water (1 mL), and sulfuric acid (10 mL)

into beaker and mix.● Measure out small sample (5 mL)● Titrate sample● Record how much titrant is used

Why is it important to have a baseline? It is important to have a baseline measurement so you know how much titrant was used in each experiment. Baseline = Final - Initial

Baseline calculation

Final Reading of burette 18.4 mL

Initial Reading of burette 14.7 mL

Baseline ( Final – Initial) 3.7 mL

Class Average Baseline 3.7 mL

2C: Uncatalyzed Rate of H2O2Discuss general procedure: ● Leave out hydrogen peroxide for 24 hours● Repeat steps in baseline

○ Add 1 mL H2O○ Add 10 mL H2SO4○ Use 5 mL of the solution for titration

● Record how much titrant is used

Final Reading of Burette 29.10 mL

Initial Reading of Burette 29.10 mL

Amount of KMnO4 titrant 3.0 mL

Amount of H2O2 spontaneously decomposed N/A

Percent of H2O2 spontaneously decomposed 18.92%

Class Average Percent of H2O2 spontaneously decomposed

N/A

2D: Enzyme-catalyzed Rate of H2O2

Independent variable: Dependent variable:Levels of IV: Time Intervals (10, 30, 60, 90, 120, 180, 360 secs)

# of trials: 10s, 90s, 120s: 4.30s, 60s, 180s: 6.360s: 10

Constants: Amount of catalase (1 mL of beef liver), Amount of H2SO4 (10 mL), Amount of H2O2(10 mL), KMnO4(type), Amount

Discuss general procedure: 10 mL H2O2 and 1 mL catalase extract were mixed together. After waiting at each of the time intervals (10, 30, 90, 120, 180, 360s), the H2SO4 was added in order to stop the reaction.What would be the control of this experiment? What is the role of sulfuric acid in this experiment? In this experiment, the solution of H2O2 and catalase were mixed and the reaction was stopped by adding the sulfuric acid. The control was 0 seconds when the sulfuric acid was added immediately after the H2O2 and catalase were mixed.

Class Data

Potassium Permanganate (mL)

Time in Seconds

10 30 60 90 120 180 360Baseline (mL) 3.70 3.70 3.70 3.70 3.70 3.70 3.70Final Reading (mL) 20.15 16.61 20.3 26.35 30.25 9.78 34.35Initial Reading (mL) 18.45 13.2 16.61 22.25 26.35 6.1 30.40Amt of KMnO4 consumed (class)

2.51 3.57 3.65 3.18 2.34 3.52 3.10

Amount of H2O2 Used (class)

-0.95 0.15 0.076 -1.9 0.65 0.15 0.17

Mention how you calculated amount KMnO4 consumed and amount of H2O2The KMnO4 (amount of titrant used) was calculated by subtracting the final and initial readings on the burette. The amount of H2O2 used was calculated by subtracting the amount of KMnO4 from the baseline.

Class Data Graph

Class Data Graph

Analysis of Data

What is the role of catalase in the reaction studied in this lab? The role of the catalase in the reaction we studied is to increase the rate of which the hydrogen peroxide decomposes.

As time increases before sulfuric acid is added to stop the reaction, what happens to the amount of H2O2 used? Explain the trend in your data.There is no definite trend in the graph. Trend in theory: As the time increases, the H2O2 used will also increase since the catalase has more time to decompose. After some time, the graph will level off as the enzyme runs out.

What would happen if catalase were not present in living tissues?Catalase is a necessity in living tissues because they increase the rate of reaction and without the enzymes being sped up, they would be too slow to function and support life.

Lab D

ebrief

Discussio

n

Questi

ons

Question Number 1

What was the limiting factor in this experiment?

Question Number 2

What was the general equation for this reaction? The specific reaction?

Question Number 3

Why was it necessary to determine a baseline for this experiment?

Question Number 4

Explain the inhibiting effect of sulfuric acid on the function of catalase. Relate this to enzyme

structure and chemistry.

Question Number 5

What does graphing the data of the amount of hydrogen peroxide usd versus time show?

Draw a sketch below and include the variables

Question Number 6

Using the formula for rate y/ x determine the initial rate of the reaction and the rates

between each point. Record in the data table below. Show work for calculation of the

initial rate.

Question Number 7What would be the effect of pH on the

enzyme? Explain.

Question Number 8

What would be the effect of temperature on the enzyme?

Question Number 9

What would be the effect of the amount of enzyme for this reaction? Explain.