Pre-Lab Activity: Milk Makes Me Sick Investigation (Part 1 of 2)

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SWBAT label and create a written narration of a model that depicts enzymatic activity in the human body in preparation for a laboratory investigation.

Big Idea

What is happening to your breakfast as we speak? Without enzymes, your favorite donut would end up a rotting mess, but have no fear your enzymes are working overtime to ensure homeostasis throughout your body!

Video Introduction: Making Enzymes Entertaining

1 minutes

This video clips describes the lesson's attempt to engage students' attention by creating  models of enzymes and relating the Biology curriculum to their personal health regarding the condition of lactose intolerance or lactose sensitive.  This lesson is a pre-lab that will prepare students for the next lesson's lab, "Milk Makes Me Sick".

Hook - Huh, Enzymes?

5 minutes

The lesson will start with students writing that they know about enzymes.  

  • Have you heard the term before?
  • Can you explain their role in the human body?
  • What are the benefits of enzymes?

After a quick class discussion, it will be evident that the students may have heard the term enzyme before in a previous science class or a television program but very few, if any, have an understanding of the structure and function of enzymes.

Students will watch this short video clip as an introduction to the study of enzymes and record three new facts that they have learned.  At the conclusion of the video clip, students will share their facts with their lab group (a total of 4 students) so that each student will end up with at least five new facts about enzymes!  If a student did not record five facts, the class will review in a whole-group discussion to ensure all students have had the opportunity to collect this new data as an introduction to the upcoming lecture notes in the next section.

Direct Instruction - Enzymes Made Easy

20 minutes

Please have students get out a sheet of paper and title it, "Chemical Reactions and Enzymes".  These Lecture Notes will provide the class with review information regarding chemical reactions and give a detailed description of how enzymes work as biological catalysts speeding up the biochemical reactions in our bodies.

Throughout the lecture notes it is encouraged that the teacher continuously make the connection with enzyme activity and the cell's/body's effort to maintain homeostasis.  The chemical reactions that are sped up through enzymatic activity enable the body to maintain homeostasis and allow our physiological processes to occur at the rate necessary to continue life as we know it. For example, Slide 3 in the lecture notes discusses the relationship carbonic acid in the blood and respiration rate to achieve homeostasis.  This type of feedback loop should be discussed in today's lesson.

Enzymes are the key to speeding up the chemical reactions to maintain homeostasis in the human body!

Common Student Misconceptions About Enzymes:

  1. Enzymes make chemical reactions occur.  Enzymes actually lower the activation energy necessary for the reaction to take place so the reaction can occur quicker and more often.  Enzymes cannot make a reaction occur.  
  2. There are only a few kinds of enzymes that work in our bodies.   Each enzyme is specific to the chemical reaction that it catalyzes so there are hundreds of enzymes that work to speed up the hundreds of chemical reactions that are occurring in the body right now.
  3. Enzyme names are hard to understand.  Enzymes are usually named by the substrate they act upon and usually end in -ase.  There are exceptions, but most follow the naming convention of lactose is broken down by lactase and lipids are broken down with the help of lipase.
  4. The enzyme only facilitates one reaction and it is broken down and reabsorbed.  A single enzyme molecule can catalyze numerous reactions per minute and reused as long as its structure is able to perform the necessary function.

After years of teaching, educators are able to identify common student misconceptions in each of the units of curriculum.  It is important to spend time identifying the misconceptions and emphasizing the correct concepts to solidify student understanding before they become confused!  

Please view the Reflection Section above for more insight on student misconceptions.

Guided Practice - Milk Makes Me Sick Pre-Lab Activity

25 minutes

Students will be provided the Pre-Lab Reading and Questions: Milk Makes Me Sick Lab.  The pre-lab handout reviews the process of enzymes working in the digestive system, specifically the role of lactase to break down lactose (milk sugar) into glucose and galactose.  Students are encouraged to keep out their lecture notes as a reference to review the terms associated with enzymes and chemical reactions in the human body.  The background information will reinforce the lecture notes that were just presented and provide details of the procedure for Tomorrow's Lab Investigation.

Students will review their responses to the Pre-Lab Reading Activity in a partner pair-share.  Once the class has had the opportunity to discuss their responses with their partner, each pair will elect a spokesperson to share one of their answers in a popcorn-type activity rotating around the room to review the correct responses to the pre-lab questions.

The teacher will review the questions to the article that students identify as difficult in a whole-group discussion to ensure all students have had the opportunity to record the correct answers in preparation of the laboratory experiment in the next lesson.

Sample of Student Work - Pre-Lab Activity- After reviewing student work, it was evident that students were successful at completing the questions that corresponded with the exact statements in the pre-lab reading, but struggled with transferring the information into models.  This eye-opening analysis has led to a more detailed class review as the unit test approaches.  

Close - Modeling Enzymes

5 minutes

As a review of today's lesson, students will write a narrative that explains the diagram on the top of their Homework: Practice with Enzymes.  The crafting of the narrative will demonstrate not only scientific understanding of enzymes, but provide the students the opportunity to write across curriculum.  Students will vary in the degree of detail they are able to provide and all students will be encouraged to go back and review their writing to make sure that if they read their narrative to someone who had never heard of an enzyme could potentially understand the model.  Students will draft their detailed narratives as a conclusion of today's lesson.

Student Work Sample #1: this artifact provides good details and a corresponding illustrated model to support the student's understanding of the content.

Student Work Sample #2 - this artifact provides exceptional details in the narration, but did not include a model to illustrate the concept of enzyme activity.

Students will complete the remainder of the practice worksheet at home to reinforce today's lesson and in preparation of tomorrow's laboratory investigation of enzymes.