NGSS Inquiry Handout: Protein Unfolding & Denaturation

Estimated Time: 45–60 minutes Materials: Internet access, Protein Denaturation Simulation, Data collection table (provided below).

Teacher Notes & Alignment

• Target Performance Expectation: HS-LS1-1: Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.
• Science and Engineering Practice (SEP): Constructing Explanations and Designing Solutions
• Disciplinary Core Idea (DCI): LS1.A: Structure and Function - Systems of specialized cells within organisms help them perform the essential functions of life.
• Crosscutting Concept (CCC): Structure and Function - Investigating or designing new systems or structures requires a detailed examination of the properties of different materials, the structures of different components, and connections of components to reveal its function.
• Observable Evidence of Student Performance:
  • Students use the simulation to gather evidence that proteins (like hemoglobin) require a specific 3D structure to function.
  • Students observe that extreme environmental conditions (high temperature or pH changes) disrupt this structure, a process called denaturation.
  • Students construct an explanation reasoning that if a protein’s structure is altered, it can no longer perform its essential function in the body.

Part 1: Engage (The Phenomenon)

Phenomenon: A normal human body temperature is around 37°C. When a person gets a severe infection, their body temperature can spike to a high fever (e.g., 40°C or higher). If a fever gets too high, it can be life-threatening and cause organ failure. Similarly, if the blood becomes too acidic or too basic, serious medical emergencies occur. Why are these extreme conditions so dangerous at a microscopic level?

Generate Questions:

1. Based on the phenomenon, what do you think happens to the structures inside our cells when the temperature or pH gets too high or low? ____________________________ ____________________________

2. What specific questions do you have about how temperature and pH affect the body’s internal molecules? ____________________________ ____________________________

Part 2: Explore (Simulation Investigation)

In this investigation, you will use the simulation to observe a single protein molecule—hemoglobin. Hemoglobin is responsible for carrying oxygen in red blood cells. To do this job, it must maintain a very precise, folded 3D shape.

Directions:

1. Open the Protein Denaturation simulation.
2. Set the Render Mode to 3D to clearly see the complex folded structure of the protein (the smooth ribbons and helices).
3. Ensure the Temperature slider is set to 37°C and the pH slider is set to 7.4. Record the initial status in the table below.
4. Gradually increase the Temperature slider. Observe the changes to the protein’s structure and the “Protein Status” indicator. Record the temperature at which the status changes from “Functional” to “Stressed”, and then to “Denatured (Non-Functional)”.
5. Reset the Temperature to 37°C.
6. Gradually change the pH slider (both lower towards acid and higher towards base). Record the pH levels where the protein becomes “Stressed” and “Denatured”.

Data Collection Table

Part 3: Explain (Sensemaking)

Data Analysis:

1. Describe what happened to the physical shape of the hemoglobin protein as the temperature increased above 45°C. What did the ribbons and helices look like? ____________________________ ____________________________

2. This loss of 3D structure is called denaturation. Using the “Verify Claim” button in the simulation, test different hypotheses about what happens when the shape changes. Which hypothesis is correct, and why? ____________________________ ____________________________

3. Why is the specific 3D shape of a protein important for its function (e.g., carrying oxygen)? ____________________________ ____________________________

Part 4: Elaborate / Evaluate (Constructing an Explanation)

The Final Deliverable: Using the evidence you gathered from the simulation, construct a scientific explanation for why a high fever (over 40°C) or severe changes in blood pH are life-threatening.

Your explanation must include:

• A clear claim connecting temperature/pH to protein function.
• Evidence from the simulation regarding what happens to the protein’s structure at extreme temperatures or pH levels.
• Reasoning that links the concept of Structure and Function: Explain why a denatured protein (like hemoglobin) can no longer carry out its essential job in the specialized cells of the body.

Explanation: ____________________________ ____________________________ ____________________________ ____________________________ ____________________________ ____________________________

Extension Option: Think about how food is cooked. When you fry an egg, the clear egg white turns solid and white. Based on what you learned about protein denaturation, explain what is happening to the proteins in the egg white when heat is applied.