Amoeba Sisters video recap worksheet on viruses and viral cycles.

Let's go through the Amoeba Sisters Video Recap: Viruses worksheet and solve each part step by step. The questions focus on virus structure, the lytic cycle, and the lysogenic cycle.

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🔹 Question 10: Virus Structures

> *Viruses come in many different structures. What would these different virus structures likely have in common? What might be different?*

Answer:

- What they have in common:
All viruses contain genetic material (DNA or RNA) enclosed in a protein coat called a capsid. Some may also have an envelope made from the host cell membrane.

- What might be different:
- Shape of the capsid (e.g., helical, icosahedral, complex).
- Presence or absence of an envelope.
- Type of genetic material (DNA vs. RNA).
- Number and type of proteins in the capsid.

✔ So, the correct answer is:
> *"All of these viruses would still have genetic material, either in the form of DNA or RNA."*
> *(This is already filled in – it's accurate.)*

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🔹 The Lytic Cycle

Now we need to illustrate the steps of the lytic cycle based on the descriptions provided.

#### Step-by-step process:

| Description | Diagram (Illustration) |
|-----------|------------------------|
| 11. The virus attaches to the host cell. | Draw a virus with its tail fibers attaching to the surface of a host cell. |
| 12. The virus injects its genetic material into the host cell (or the virus itself may be taken inside the cell where its genetic material will be used by the host). | Show the virus injecting DNA/RNA into the host cell. If enveloped, show it entering via endocytosis. |
| 13. Based on the viral genetic instructions, the host manufactures and assembles copies of the virus. | Inside the host cell, draw multiple new viral components being built: capsids, envelopes, genetic material, etc. |
| 14. The newly formed viruses can lyse (burst) the host cell and now infect new host cells. | Show the host cell bursting open, releasing many new viruses that go off to infect other cells. |

📌 Note: Since this is a written response, I’ll describe what you should draw:

- Step 11: A bacteriophage (for example) with tail fibers touching the bacterial cell wall.
- Step 12: The viral DNA entering the cell; the phage head detaches.
- Step 13: Inside the host, viral parts are assembled using host machinery.
- Step 14: Host cell ruptures (lysis), releasing new viruses.

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🔹 The Lysogenic Cycle

> *Compare this illustration to how the lysogenic cycle would be different from the lytic cycle.*

The illustration shows "Operation Infiltration" — a virus inserting its DNA into the host genome.

#### Key Difference:

In the lysogenic cycle, instead of immediately producing new viruses and lysing the cell:
- The viral DNA integrates into the host chromosome → becomes a prophage (in bacteria).
- The host cell continues to divide normally, passing the viral DNA to daughter cells.
- The virus remains dormant until triggered (e.g., UV light, chemicals) to enter the lytic cycle.

#### Fill-in-the-blank Answer:
> "The distinction between lysogenic and lytic cycles is that in lysogenic cycles, viral DNA spreads by normal cellular replication, while in lytic cycles, several copies of the virus are produced rapidly and the cell is killed."

✔ This sentence is already partially filled in. You just need to complete the blanks:

> Answer:
> *The distinction between lysogenic and lytic cycles is that in lysogenic cycles, viral DNA spreads by normal cellular replication, while in lytic cycles, several copies of the virus are produced rapidly and the cell is killed.*

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✔ Summary of Answers:

#### Q10:
- Common feature: All viruses have genetic material (DNA or RNA) and a protein capsid.
- Differences: Shape, presence of envelope, type of nucleic acid, method of entry.

#### Lytic Cycle Diagrams (Steps 11–14):
1. Attachment: Virus binds to host receptor.
2. Penetration: Genetic material injected or whole virus enters.
3. Replication & Assembly: Host makes viral parts → assemble new viruses.
4. Release: Cell lyses → new viruses released.

#### Q15: Lysogenic vs. Lytic Cycle
> *The distinction between lysogenic and lytic cycles is that in lysogenic cycles, viral DNA spreads by normal cellular replication, while in lytic cycles, several copies of the virus are produced rapidly and the cell is killed.*

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🎯 Final Tip:

If you're drawing the diagrams:
- Use simple shapes for viruses and cells.
- Label key parts: capsid, DNA, host cell, new viruses.
- For lysogenic cycle: show viral DNA integrating into host chromosome.

Let me know if you'd like a printable version or visual sketch guide!