Chapter 7. A Day at the Beach

Instructor's Notes

Instructor Notes for “A Day at the Beach”, Lipid Metabolism Case Study

Topic Pre-requisites: Students should have exposure to the topics of Chapters 14-17 in Lehninger POB, 7^th ed.

Overview

This case is designed to help students understand the importance of fatty acid transport into mitochondria, the role of carnitine in this process, and the interconnections between carbohydrate and lipid metabolism in humans. The case also explores the roles of the hormones insulin and glucagon in regulating energy metabolism in humans. As such, we have anticipated that students will have been exposed to material in the textbook through Chapter 17 of Lehninger POB, 7^th ed. before beginning the case. Students may work individually or in groups to complete this case study. Students are constantly encouraged to refer to their textbook throughout the case, and internet access is permitted, although it is not necessary for the completion of the case. Students are required to iteratively acquire, analyze, and integrate data as they progress through the case and answer assessment questions found throughout the case. All assessment questions are automatically scored.

The case will also keep track of the number of investigations that students conduct and report this number to the instructor; students are made aware of this fact as a means to encourage careful consideration of investigation options and discourage guessing. It is entirely up to the instructor what to do with this information; we suggest potentially rewarding students who efficiently solve the case and/or penalizing students who obviously relied on blanket guessing (evident by the use of all or nearly all investigative options). For reference: there are 34 total investigative options within the case and 13 are minimally required to complete the case. We anticipate that careful students will typically make use of 15-20 options in solving this case.

Learning Objectives

This case is intended for remediating or extending these student capabilities:

1. The real-world application of the study of human metabolism. Students will:

• utilize real biochemical tests to evaluate and ‘solve’ a metabolic disorder case.
• consider the importance of factors like personal and family history, diet, medications taken, and symptoms in solving a biochemical case.

2. Making connections between carbohydrate and fat metabolism in humans. Students should be able to:

• outline and explain the importance of carnitine-mediated fatty acid transport into mitochondria.
• review fatty acid metabolism pathways and regulation.
• explain the importance of ketone body formation in human metabolism.

3. Practicing critical thinking skills involving data. Students will:

• evaluate data provided by metabolite and enzyme tests.
• integrate multiple pieces of biochemical data.

Some questions are designed to show areas of difficulty for students

• Students often struggle with predicting the changes in flux through various metabolic pathways as a result of different nutritional states (and resultant hormone levels). This is particularly challenging when multiple tissues are considered. This issue is addressed in numerous assessment questions throughout the case.
• Students often harbor misconceptions about ketone body formation, specifically about its purpose and cause(s). This issue is addressed in multiple assessment questions throughout the case.
• Author note: A common error is to jump immediately into testing a ‘pet’ hypothesis by conducting laboratory tests (metabolite assays or enzyme assays) before exploring ‘data gathering’ options like visual inspections, or simply interviewing the person. This is an excellent and intentionally designed opportunity to point out a common mistake about the scientific method--that is, it begins with making careful observations, rather than by immediately testing quickly formed hypotheses.

Suggested implementation

Below we describe two options for course implementation. The hybrid Online/In-class approach is recommended. Time required for students to complete the online case will vary by group depending on the level of discussion between each investigation. The case study can be started and stopped, and so it is recommended to give students a window of 3-5 days in which to complete the assignment.

Hybrid: Online/In-class (recommended approach; ~30 minutes of class-time expected):

1. Share the case study link with your students to use to work online outside of class, preferably in pairs or groups of three. Assign the case study to be due before your next class meeting. Students should be instructed to bring copies of notes, and/or printed answers to assessment questions to the following class period.

2. Review the online answers before the following class for difficult areas for students (see expected areas of difficulty above).

3. Lead students in a discussion in pairs, groups, or as a class (depending upon class size and instructor preference) to address unresolved difficulties (~30 minutes in-class time).

4. We recommend using the supplied assessment questions on exams or as homework assignments to reinforce the difficult concepts covered. Please see the document “Exam Questions Case 3- Lipid Metabolism”

Online only approach (minimal in-class time required):

1. Share the case study link with your students to work online, preferably in pairs or groups of three. Assign the case study to be due before your next class meeting.

2. Review the online answers for difficult areas for students (see expected areas of difficulty above).

3. Mention or remediate tough points during a portion of lecture.

4. We recommend using the supplied assessment questions on exams or as homework assignments to reinforce the difficult concepts covered. Please see the document “Exam Questions – A Day at the Beach - Lipid Metabolism Case.”

Suggestions for in-class discussions (these questions may also be used in summative assessments such as exams or scored quizzes

• What were some of the most important facts in the initial presentation of Jessie’s case and why were they important?
  • Students could be directed to brainstorm in groups or as a whole class.

• What were some of the most important facts of Jessie’s case that were revealed as a result of your investigations and why were they important?
  • Students could be directed to brainstorm in groups or as a whole class.

• Does Jessie suffer from an inborn error of metabolism? Explain your answers. How was she able to be a successful athlete in her past?
  • This question could be easily used as a think-pair-share exercise.
  • Alternatively, this question could first be answered in writing by individual students and then those responses collected or discussed in groups and revised.

• What was the relevance of Jessie’s diet in this case?

• Why did Jessie’s liver show increased fat deposition?

• Why was Jessie unable to make ketone bodies during a fasting study and why was she suddenly able to create ketone bodies when given short-chain fatty acids?
  • This question could be easily used as a think-pair-share exercise.

• Why did Jessie have abnormally low blood glucose during a fasting study?
  • Students could be directed to brainstorm in groups or as a whole class.

You are missing vital information

You may be missing vital information needed to sufficiently explain this incident. You must complete all investigations before proceeding to the final assessment questions.

You are missing vital information

You may be missing vital information needed to sufficiently explain this incident. You must complete all investigations before proceeding to the final assessment questions.

This activity has already been completed, however feel free to review the information contained within.

I am finished gathering information for this investigation and feel I am able to fully explain the reason(s) for Jesse’s incident in biochemical and physiological terms, and I can fully justify and completely explain my reasoning based on the evidence I have gathered.