Phenomenon: How Do Viruses Protect and Deliver Their Genetic Instructions?

Viruses are tiny, intricate machines that exist on the edge of life. Although they cannot reproduce on their own, they are highly effective at delivering instructions (genetic material like RNA or DNA) into a host cell. To survive the journey outside of a host cell, this genetic material is packaged inside a highly organized protein shell called a capsid.

In this activity, you will use the Virus Capsid Explorer to investigate the structure and function of various viruses. You will observe how regions of genetic information (RNA) are enclosed by protective proteins, and how the overall architecture of these specialized structures enables the virus to function.

1. Engage

Think about a package being delivered in the mail.

1. What role does the cardboard box play in relation to the fragile item inside? _____
2. How might a virus’s “package” (the capsid) be similar or different from a cardboard box? _____

2. Explore

Open the Virus Capsid Explorer simulation.

1. Select a Virus: Use the dropdown menu to select Satellite Tobacco Mosaic Virus.
2. Interact with the Model:
   • Use your mouse/touchpad to click and drag to rotate the virus structure in 3D.
   • Scroll to zoom in and out.
3. Structure Toggles:
   • Uncheck Viral Capsid (Proteins). What remains visible? _____
   • Re-check the Viral Capsid and lower the Opacity (Slicing) slider to 0.5. Describe what you see inside the shell: _____
4. Visualization Styles: Click through the different visualization styles.
   • Which style helps you best see the individual atoms (Spacefilling)? _____
   • Which style helps you see the overall secondary structure of the proteins (Cartoon)? _____
5. Record Data: Click Record Data to add this virus to your Data Table.

Repeat the steps above to explore at least three other viruses from the list, including Bean Pod Mottle Virus and Tomato Aspermy Virus. Record their data.

3. Explain

Data Collection

Note: You can click “Export to CSV” in the simulation to save your full dataset.

Analysis Questions

1. Look at the relationship between Genome Length and Capsid Proteins. Do larger genomes generally require more capsid proteins to enclose them? _____
2. All cells and many viruses contain genetic information (like DNA or RNA) that codes for the formation of proteins. In the virus models, where is the genetic material located relative to the proteins? Why is this structural arrangement necessary for the virus’s function? _____
3. In multicellular organisms, specialized cells (like muscle or nerve cells) use proteins to carry out essential functions. How does the structure of a virus capsid, built from proteins, carry out its essential function of protecting the genome? _____

4. Elaborate

If a mutation occurred in the virus’s RNA (the genetic instructions) that changed the shape of the capsid proteins, what might be the consequence for the virus? Think about how the structure of the resulting protein relates to its function. _____

5. Evaluate: Final Deliverable

Construct an Explanation Write a short paragraph explaining the relationship between genetic material (RNA/DNA) and proteins, using the viral capsid as a model. Your explanation must include:

• Evidence that genetic material (genes) provides the instructions for building proteins.
• An explanation of how the physical structure of the proteins determines their function (e.g., forming a protective shell).
• Reasoning that connects changes in the genetic sequence to potential changes in protein structure and overall function.

Teacher Notes

Alignment to NGSS:

• 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 Practices: Constructing Explanations and Designing Solutions
• Disciplinary Core Ideas:
  • LS1.A: Structure and Function - All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins.
• Crosscutting Concepts: Structure and Function, Cause and Effect

Evidence Statement Alignment: This task provides an interactive model allowing students to gather evidence and construct an explanation demonstrating the following elements of HS-LS1-1:

• All cells contain DNA / DNA contains regions called genes: Students observe that viruses, while not cells, contain genetic material (RNA in these models, functioning analogously to DNA in cells by storing genetic instructions).
• The sequence of genes contains instructions that code for proteins: The task explicitly asks students to link the RNA genome length and sequence to the production of the capsid proteins.
• Groups of specialized cells (tissues) use proteins to carry out functions that are essential to the organism: Students model how proteins form specialized structures (the capsid shell) that perform a specific, essential function (protecting the genome).
• Gene sequence affects protein function: In the Elaborate section, students reason about how mutations in the genetic instructions would alter the physical structure of the capsid proteins, thereby impairing their protective function.

Estimated Time: 45 minutes Materials: Device with internet access to run the Virus Capsid Explorer simulation.