enzymes in action - texas a&m university

TCCRI College Readiness Assignments Instructor Task Information

Texas College and Career Readiness Initiative 1 ©2009 Texas Higher Education Coordinating Board. All rights reserved. Draft October 2009

Enzymes in Action

Overview

Description

In this activity, students are asked to collect background information regarding the structure and functioning of enzymes. The students will then explore enzymes in the laboratory setting. The activity also allows students the opportunity to design and conduct a lab to measure the impact of a single variable such as temperature, pH, and substrate concentration on enzyme activity.

Final Product: After completing the investigation, students will prepare a written report of the lab results.

Course

Biology

Task Level

Grade 10–12

Cross-Disciplinary Standards Assessed

I. Key Cognitive Skills

A.1. Engage in scholarly inquiry and dialogue.

B.2. Construct well-reasoned arguments to explain phenomena, validate conjectures, or support positions.

B.3. Gather evidence to support arguments, findings, or lines of reasoning.

B.4. Support or modify claims based on the result of inquiry.

C.1. Analyze a situation to identify a problem to be solved.

C.3. Collect evidence and data systematically and directly relate to solving a problem.

D.1. Self-monitor learning needs and seek assistance when needed.

D.2. Use study habits necessary to manage academic pursuits and requirements.

D.3. Strive for accuracy and precision.

D.4. Persevere to complete and master tasks.

E.1. Work independently.

E.2. Work collaboratively.

Enzymes in Action Instructor Task Information


F.1. Attribute ideas and information to source materials and people.

F.2. Evaluate sources for quality of content, validity, credibility, and relevance.

II. Foundational Skills

B.1. Write clearly and coherently using standard writing conventions.

B.3. Compose and revise drafts.

C.4. Evaluate the validity and reliability of sources.

E.1. Use technology to gather information.

Science Standards Assessed

I. Nature of Science: Scientific Ways of Learning and Thinking

A.2. Use creativity and insight to recognize and describe patterns in natural phenomena.

B.1. Design and conduct scientific investigations in which hypotheses are formulated and tested.

C.3. Demonstrate skill in the safe use of a wide variety of apparatuses, equipment, techniques, and procedures.

D.1. Demonstrate literacy in computer use.

D.3. Demonstrate appropriate use of a wide variety of apparatuses, equipment, techniques, and procedures for collecting quantitative and qualitative data.

E.2. Use essential vocabulary of the discipline being studied.

III. Foundation Skills: Scientific Applications of Communication

A.1. Use correct applications of writing practices in scientific communication.

B.2. Set up apparatuses, carry out procedures, and collect specified data from a given set of appropriate instructions.

C.1. Prepare and present scientific/technical information in appropriate formats for various audiences.

D.1. Use search engines, databases, and other digital electronic tools effectively to locate information.

VI. Biology

B.2. Describe the structure and function of enzymes.

Objectives

Students will:

• Describe an enzyme in terms of its function in chemical reactions and substrate/product relationships.



• Define and recognize examples of the following terms related to enzymes: catalysts, active site, substrate, product, induced fit, competitive inhibition, noncompetitive inhibition, activation energy, and feedback inhibition.

• Design and conduct investigations to measure the effect on initial reaction rates produced by changes in temperature, pH, enzyme concentration, or substrate concentration.

• Communicate the results of an investigation measuring the effect of a manipulated variable such as temperature, pH, enzyme concentration, or substrate concentration.

Preparation

• Read the Instructor Task Information and the Student Notes.

• Prepare student copies of the Student Notes pages, Introduction to Enzymes WebQuest, Introduction to Enzyme Action, and Lab Report Grading Rubric handouts.

• Identify key words that students can use to conduct their Internet search. You may want to list several Web site addresses to help direct students as they conduct their Internet research.

• Secure computer access necessary for web search.

• Gather lab equipment and supplies needed for both the preliminary investigation and the student inquiry investigation.

• Provide students with copies of the preliminary investigation protocol.

Prior Knowledge

In order to be successful in these activities students need to be able to:

• Safely handle chemicals in the laboratory.

• Understand the structural composition of a protein.

• Recognize biological macromolecules.

• Design a data table for collection of experimental data.

• Prepare a graphical representation of data collected.

Vocabulary

• Activation energy

• Active site

• Catalyst



• Competitive inhibition

• Enzymes

• Enzyme-catalyzed reaction

• Feedback inhibition

• Induced fit

• Noncompetitive inhibition

• pH

• Product

• Substrate

Time Frame

This assignment will require approximately 12 days to complete. Eight of the days will require time during the instructional period. Students are expected to prepare their lab reports outside of class. If class time is limited, students can also conduct their web search outside of class.

Day 1: Introduce enzymes. Begin enzyme web search.

Day 2: Continue enzyme web search.

Day 3: Web search due at end of class.

Day 4: Conduct preliminary enzyme lab.

Day 5: Design Enzyme Inquiry Lab.

Day 6: Finalize design. Peer review design.

Day 7: Conduct Enzyme Inquiry Lab.

Day 8: In class, explain the lab report expectations.

Day 9–12: Outside of class time, students will prepare lab report. Report due at the end of class on day 12.

The Introduction to Enzyme Action lab could be done as early as day one in this sequence.



Instructional Plan

Getting Started

CCRS Performance Expectations

Cross-Disciplinary Standards:


A.1. Engage in scholarly inquiry and dialogue.










F.2. Evaluate sources for quality of content, validity, credibility, and relevance.


C.4. Evaluate the validity and reliability of sources.

E.1. Use technology to gather information.

Science Standards:


D.1. Demonstrate literacy in computer use.




D.1. Use search engines, databases, and other digital electronic tools effectively to locate information.

VI. Biology




Learning Objectives

Students will:

• Describe an enzyme in terms of its function in chemical reactions and substrate/product relationships.

• Define and recognize examples of the following terms related to enzymes: catalysts, active site, substrate, product, induced fit, competitive inhibition, noncompetitive inhibition, activation energy, and feedback inhibition.

Procedure

1. Use an enzyme model, video clip, or instructor-made presentation to teach the components of an enzyme-catalyzed reaction, including the enzyme, substrate, enzyme/substrate complex, product, reactant, and induced fit.

2. Have students practice explaining the catalytic cycle using the think-pair-share strategy or similar active student engagement strategy as they answer the following questions:

a. What is the relationship between an enzyme and a substrate molecule?

b. Would a substrate be a product or reactant in an enzyme-catalyzed reaction?

c. Describe induced fit.

d. How are competitive inhibition and non-competitive inhibition similar? How are they different?

e. Draw an enzyme/substrate complex formed during the reaction in which catalase catalyzes the decomposition of hydrogen peroxide into water and oxygen.

3. Lead students in a web search to expand their understanding of enzymes, activation energy, and forms of inhibition. See the Introduction to Enzymes WebQuest handout. If possible, the handout should be provided in an electronic version for student access. The following terms will help students narrow the search:

a. Question 1 – macromolecule enzyme

b. Question 2 – enzymes found in human body

c. Question 3 – enzyme specificity definition

d. Question 4 – activation energy

e. Question 5 – factors affecting enzyme activity

f. Question 6 – enzyme inhibition



4. Class discussion may be needed to address the issues of Web site reliability, plagiarism, and the need to cite references on the answer document.

Investigating
















Science Standards:



B.1. Design and conduct scientific investigations in which hypotheses are formulated and tested.

C.3. Demonstrate skill in the safe use of a wide variety of apparatuses, equipment, techniques, and procedures.

D.3. Demonstrate appropriate use of a wide variety of apparatuses, equipment, techniques, and procedures for collecting quantitative and qualitative data.


B.2. Set up apparatuses, carry out procedures, and collect specified data from a given set of appropriate instructions.



VI. Biology


Learning Objectives

Students will:

• Design and conduct investigations to measure the effect on initial reaction rates produced by changes in temperature, pH, enzyme concentration, or substrate concentration.

Procedure

1. Students will begin by conducting a guided inquiry investigation of enzyme activity to gain the experience needed to design an experiment on factors affecting the rate of enzyme activity. See the protocol as described in the Introduction to Enzyme Action handout.

2. In the post-lab class discussion and lab questions, students should express understanding of the functioning of a typical enzymatic pathway.

3. Lead a discussion in which students predict the impact of a change in pH, temperature, or concentration on the activity of an enzyme.

4. Allow students time to work in small groups to formalize predictions, write a hypothesis, and design an experiment to test the hypothesis.

5. The following day, students should exchange their experimental designs that include the experimental protocol and conduct a peer review of the design. Discuss with students the components they should check for as they perform the peer review.

6. Students should edit their reviewed protocols and then conduct the investigation.

Drawing Conclusions




B.2. Construct well-reasoned arguments to explain phenomena, validate conjectures, or support positions.













Science Standards:






C.1. Prepare and present scientific/technical information in appropriate formats for various audiences.

VI. Biology


Learning Objectives

Students will:

• Communicate the results of an investigation measuring the effect of a manipulated variable such as temperature, pH, enzyme concentration, or substrate concentration.

Procedure

1. Describe the attributes of the components expected to be found in a formal lab report.

2. Review the lab report grading rubric with students to ensure that all students understand the report expectations.

3. Devote 3–5 minutes at the beginning or ending of the class period over the next several days to answer student questions regarding the preparation of the lab report.

4. Remind students as the lab report due date approaches.

5. (Optional) Set aside class time to have student conduct a peer review of a rough draft of the lab report.



Scaffolding/Instructional Support The goal of scaffolding is to remove support gradually to encourage student success, independence, and self-management. The following suggestions are examples of scaffolding that can be used by instructors to meet diverse student needs while students are completing this assignment:

• Some students will benefit from being provided a list of questions that should be answered in the body of a well-written conclusion section such as:

• What general data trends were found?

• Is your hypothesis supported or not supported?

• What were possible sources of errors?

• What changes would you now make to the protocol?

• What additional questions have been generated by your results?

• The rigor of the experimental design would be raised by expecting students to test additional variables. A second way to increase the rigor would be to add an additional enzyme. For example, the impact of increased temperature could be measured using the enzyme catalase and then, in a second phase of the lab, using the enzyme lactase.



Solutions The solutions provided in this section are intended to clarify the problem for instructors. These solutions may not represent all possible strategies for approaching the problem or all possible solutions. It should be used for reference only.

Students should use reliable Web sites as sources when completing the Introduction to Enzymes WebQuest handout.

Students should design a controlled experiment to test a single variable. Make sure students identify their control group.

TCCRI College Readiness Assignments Student Notes

Texas College and Career Readiness Initiative S-1 ©2009 Texas Higher Education Coordinating Board. All rights reserved. Draft October 2009

Enzymes in Action

Introduction Enzymes are proteins that catalyze a myriad of chemical reactions in living organisms. Enzymes are key players in the process of chemically breaking down food in the digestive system. Enzymes also regulate processes such as DNA replication, cellular respiration, and photosynthesis. An understanding of enzymes is vital to understanding the complex chemical pathways that occur within living cells.

In this activity, you will explore the fundamental concepts associated with enzymes and enzymatic regulation. In addition, you will explore the chemical reactivity of enzymes such as catalase. You will also have the opportunity to design an investigation to explore the impact of pH, temperature, or concentration on enzyme activity. The results of your investigation, as well as your investigational design, will be communicated through a formal lab report.

Directions

Getting Started

1. Listen to your instructorʼs introduction to enzyme-catalyzed reaction. Participate in a think-pair-share discussion in which you answer the provided questions.

2. Access the Internet as instructed by your instructor.

3. Complete the Internet-based search activity handout, Introduction to Enzymes WebQuest.

4. Submit the completed handout.

Investigating

1. Conduct the initial observational lab activity, Introduction to Enzyme Action.

2. Answer the questions on the handout and write the summary paragraph.

3. Submit your completed handout and summary paragraph.

4. After a discussion within your lab group, select one of the following variables to further investigate: pH, temperature, substrate concentration, or enzyme concentration.

5. Review the Lab Report Grading Rubric handout, and work with your lab partners to design a controlled experiment to test the selected variable.

Enzymes and Their Function Student Notes

Texas College and Career Readiness Initiative S-2 ©2009 Texas Higher Education Coordinating Board. All rights reserved. Draft October 2009

6. Exchange your experimental design with another group for review.

7. Edit your design based on the peer review, and conduct the controlled experiment, collecting all necessary data.

Drawing Conclusions

1. Prepare a formal lab report detailing your experiment.

2. Submit your lab report.

TCCRI College Readiness Assignments Student Handouts

Texas College and Career Readiness Initiative SH-1 ©2009 Texas Higher Education Coordinating Board. All rights reserved. Draft October 2009

Introduction to Enzymes WebQuest

Use your Internet research skills to find valid answers to each of the following questions or tasks. Cite the sources of each answer in the space provided by each item.

1. Describe the biochemical composition of an enzyme and identify the macromolecule group for enzymes.

Citation:

2. Identify 5 enzymes in the human body and list the substrate(s), product(s) of the reaction catalyzed by each enzyme, and the typical location of the enzyme in the human body.

Enzyme Substrate(s) Product(s) Location in Body 1.

2.

3

4.

5.

Citation:

3. Explain what is meant by the phrase “enzyme specificity.”

Citation:

Enzymes in Action Student Handouts


4. Describe activation energy and explain how it is impacted by an enzyme. Draw a graph to support your explanation.

Citation:

5. Identify 3 factors that can influence the rate of an enzyme-catalyzed reaction. Describe how each factor affects the rate.

Citation:



6. Describe and give a specific enzyme-related example of each of the following terms.

a. Feedback inhibition:

Example:

Citation:

b. Competitive inhibition:

Example:

Citation:

c. Non-competitive inhibition:

Example:

Citation:

d. Allosteric regulation:

Example:

Citation:



Introduction to Enzyme Action

Enzymes catalyze a wide variety of reactions in living organisms. These proteins serve as catalysts lowering the energy of activation for a particular reaction. Enzymes have an active site with a structural arrangement that allows only specific substrate molecules to attach. As a result, enzymes exhibit specificity to a particular substrate or reactant in a chemical reaction. For example, the enzyme lactase is specific to the substrate molecule lactose, helping break it into the products glucose and galactose. Similarly, the enzyme sucrase is specific to the substrate sucrose.

In this activity, you will identify the specific substrate molecule for the enzyme catalase. The presence or absence of enzyme activity will be determined by observing the appearance of product molecules.

Materials:

• 4 test tubes

• Test tube rack

• 1 mL syringe

• 10 mL syringe

• 10 mL distilled water

• 10 mL ethanol

• 10 mL 95% acetic acid (vinegar)

• 10 mL hydrogen peroxide

• 10 mL 5% sodium chloride solution

Procedure:

1. Discuss with your lab group which of the four chemicals provided will serve as a substrate for the enzyme catalase and then formulate and record your hypothesis below.

Hypothesis:

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

2. Obtain four clean test tubes and place 10 mL of each of the four test chemicals into four separate test tubes. Be sure to thoroughly rinse the syringe as you move



from one chemical to the next.

3. Add 1 mL of catalase solution to the test tube containing ethanol. Observe the reaction and record your observations.

4. Repeat step 3 using acetic acid, hydrogen peroxide, and sodium chloride solutions.

5. Repeat steps 3 and 4 using distilled water instead of the catalase solution.

6. Record your observations and answer the questions below:

Data:

Observations

Chemical Catalase Added Distilled Water Added

Ethanol

Acetic Acid

Hydrogen Peroxide

Sodium Chloride

Discussion Questions:

1. Which chemical produced the most obvious reaction when catalase was added?

2. Was your hypothesis supported by the observations? Explain.

3. On a separate sheet of paper, prepare a paragraph summarizing your results and understanding of enzyme activity. Use the following terms in your summary statement: substrate, product, reactant, activation energy, and catalyst. Additionally, identify the enzymes, substrate, and products of the reaction observed in this activity.



Lab Report Grading Rubric

REPORT ITEM

POSSIBLE POINTS

EARNED POINTS/comments

Title 3 Introduction (12) Background information 4 Purpose of the experiment 4 Hypothesis 4 Materials and Procedures (15)

Materials listed 5 Procedures stated 5 Control(s) identified 5

Results/Data Collection/Analysis (20) Data recorded in tables 8 Graph(s) present 6 Titled 2 Axes labeled 2 Variables correctly identified 2 Conclusion (16) Results aummarized 4 Errors identified 4 Conclusion stated 4 Improvements recommended 4 Literature Citation (4) Cited within write up 2 Citation information correct 2 Questions (30) Questions written 10 Correctness 20 Comments

TOTAL POINTS (100)

enzymes in action - texas a&m university

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