ENZYME KINETICS

• Students in introductory biology classes often have difficulty

understanding many aspects of enzymes.

•Since the physiology of organisms is based on the existence and speed of chemical reactions, it is essential to understand basics in enzyme activity in order to understand how life can exist.

•As students discover the importance of enzymes, they are better prepared to apply their knowledge to real world applications.

•Study of enzymes is a difficult topic for most students because it is an intangible topic.

BACKGROUND

Objectives

To allow students to learn science through the process of discovery

To provide a representation of how one of life’s basic processes occur

To motivate learners to make their own discoveries of knowledge

Enzyme Salad Lab

Background Information Enzymes

Effect of temperature

Gelatin

Pineapple

Pre-Lab Discussion

Rationale Time Objectives Materials Procedure

TUBE CONTENTS RESULTS

1. Gelatin and Fresh Pineapple

2. Gelatin and Canned Pineapple

3. Gelatin and Frozen Pineapple

4. Gelatin

DISCUSSION QUESTIONS

1. Why did test tube #4 contain only gelatin?

2. What could account for the different results in the tubes?

3. How could the canning process change bromelin?

4. What other fruits contain protein-digesting enzymes?

5. Using fresh pineapple, determine the temperature at which the enzyme denatures. (for HS and college students)

6. Design an experiment to find a temperature at which a meat tenderizer works the best. (for college

students)

NOTES

1. We usually do this lab when we are discussing digestive enzymes and temperature dependence of enzymes. The students like the application of biochemistry to something they eat.

2. Suggestions:

a. Preparing the gelatin: Stir two envelopes of unflavored gelatin into 800 ml of hot water. This should be enough for three classes. Store it in a warm water bath when the students are using it so it will pour easily.

b. Remind the students to rinse of the razor blade between types of pineapple. Clean up is easier if they cut the fruit on paper plates.

c. Canned Pineapple: Use the chunky style.

Application of the Enzyme Kinetics

• •All of the three activities comes with quiz questions to be completed after the

experiment. These questions will be used to evaluate the learning experience for the class.

•The concepts explored will apply to different students at different levels. For example, the concept of a reaction mechanism is too complex for

elementary or even some high school students to understand. Thus, quantitative analysis of the kinetics is reserved to the college level.

• The experiment provides a big picture of the framework of the basic concepts of enzyme kinetics: what enzymes are, how they work, and how

they can be used.

The DISCOVERY APPROACH

The discovery approach was first popularized by Jerome Bruner in a book The Process of Education

The concept behind the discovery approach is that the motivation of pupils is to learn science will be increased if they experience the feelings scientists obtain from "discovering" scientific knowledge

The idea was supported by the notion that pupils would learn about the nature of science, and the formation of scientific knowledge through the process of "discovery"

In a Discovery Lesson…

the lesson proceeds through a hierarchy of stages which may be associated with Bruner's levels of thought

• the teacher decides the concept, process, law or piece of scientific knowledge which is to be "discovered“

3 Stages of the Discovery Approach

• Enactive Level

• Ikonic Level

• Symbolic Level

J. BRUNER

Enzyme Kinetics for 3 School Levels

Level Achievement of Learning Goals Skill Sets

PrimaryMake a distinction between the controls and

variables of the experiment in order to conclude the presence of enzymes

Scientific ObservationRecord KeepingFollowing Instructions

HighSchool

Recognition of the Enzyme-Substrate ComplexAnalysis of Temperature Sensitivity of the

EnzymeRecognition of the effect of denaturation on

enzyme activity

Hypothesis DevelopmentScientific Inference

College

Perform a detailed experiment with quantitative analysis

Justify modeling equations with experimental results

Use graphical methods on MS Excel to quantify the results

Data AnalysisReaction MechanismsTeamwork

References

Balala, S. (2003). Activities-To-Go. www.acessexellence.org. Retrieved on December 4, 2006. http://accessexellence.org/AE/ATG

Collette, A. and Chiapetta, E. (1994). Science Instruction in the Middle and Secondary Schools. New York, USA: Macmillan Publishing Company.

Duit, R. (2002). Pineapple-Jell-O Lab. www.dev.mdk12.org. Retrieved on December 6, 2006. http://dev.mdk12.org/instruction/curriculum/hsa/biology/enzyme_activity/ teachers_guide_evaluation.html

Scott, S. Mixed Plate Biology. (2004). www.woodrow.org. Retrieved on December 4, 2006. http://woodrow.org/teachers/aelm