amoeba sisters video recap: viruses
10. viruses come in many different structures. what would these different virus structures likely have in common? what might be different?

the lytic cycle
it is time to focus on how viruses reproduce by exploring the lytic cycle! for the following question numbers, illustrate the scenario described to show the virus and host cell.
the virus attaches to the host cell. 11. the virus inserts 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). 12.
based on the viral genetic instructions, the host manufactures and assembles copies of the virus. 13. the newly formed viruses can lyse the host cell and now infect new host cells. 14.
the lysogenic cycle
15. can you relate this illustration to how the lysogenic cycle would be different from the lytic cycle?

Question

amoeba sisters video recap: viruses
10. viruses come in many different structures. what would these different virus structures likely have in common? what might be different?

the lytic cycle
it is time to focus on how viruses reproduce by exploring the lytic cycle! for the following question numbers, illustrate the scenario described to show the virus and host cell.
the virus attaches to the host cell. 11. the virus inserts 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). 12.
based on the viral genetic instructions, the host manufactures and assembles copies of the virus. 13. the newly formed viruses can lyse the host cell and now infect new host cells. 14.
the lysogenic cycle
15. can you relate this illustration to how the lysogenic cycle would be different from the lytic cycle?

Accepted Answer

# Brief Explanations:
### Question 10:
- **Common Features**: All viruses typically have genetic material (either DNA or RNA) and a protein coat (capsid). Some may also have an envelope (a lipid bilayer from the host cell membrane, with embedded viral proteins) around the capsid.
- **Different Features**: The shape of the capsid can vary (e.g., helical like Tobacco Mosaic Virus, icosahedral like Rhinovirus, or complex like Bacteriophage). The type of genetic material (DNA vs. RNA, single - stranded vs. double - stranded) can differ. The presence or absence of an envelope is also a distinguishing factor (e.g., Influenza has an envelope, while Rhinovirus does not). The host range (some infect bacteria, others plants or animals) and the specific proteins on the surface (which determine host cell recognition) can also vary.

### Question 11 (Lytic Cycle Step):
After the virus attaches to the host cell (first step), the next step is usually the entry of the virus or its genetic material into the host cell. For example, in bacteriophages, the tail fibers attach to the bacterial cell wall, and then the tail sheath contracts to inject the phage DNA into the bacterial cell. For animal viruses, some may be endocytosed (the host cell engulfs the virus in a vesicle), and then the vesicle fuses with lysosomes or the virus fuses with the host cell membrane to release its genetic material. To illustrate, you could draw the virus (with its capsid and genetic material) interacting with the host cell membrane, with arrows showing the movement of the virus or its genetic material into the cell.

### Question 12 (Lytic Cycle Step):
After the virus inserts its genetic material into the host cell, the host cell's machinery is hijacked. The viral genetic material takes control of the host cell's transcription and translation processes. The host cell stops producing its own proteins and starts producing viral proteins (like capsid proteins) and replicating the viral genetic material. To illustrate, you could show the host cell nucleus (if it's a eukaryotic host) with viral DNA being transcribed, and ribosomes in the cytoplasm translating viral mRNA into viral proteins. You could also show the host cell's DNA being ignored or inactivated.

### Question 13 (Lytic Cycle Step):
After the host manufactures viral components (proteins and new genetic material), the next step is the assembly of new virus particles. The viral capsid proteins assemble around the newly synthesized viral genetic material. For example, in a bacteriophage, the capsid proteins form the head structure, and the new phage DNA is packaged into the head. For an animal virus, the capsid assembles around the viral RNA or DNA, and if the virus has an envelope, the newly formed virus particles move to the host cell membrane (where the envelope proteins are embedded), and the virus buds off, acquiring the envelope. To illustrate, you could draw multiple new virus particles being formed inside the host cell, with capsids surrounding the genetic material, and for enveloped viruses, the budding process at the cell membrane.

### Question 14 (Lytic Cycle Step):
After the newly formed viruses lyse the host cell (breaking it open to release the new viruses), the released viruses can then go on to infect new host cells. To illustrate, you could draw the lysed host cell (with a broken cell membrane) releasing many new virus particles, and these virus particles moving towards new, healthy host cells, with arrows showing the direction of movement and the attachment process starting on the new host cells.

### Question 15 (Lysogenic Cycle Comparison):
- **Lytic Cycle**: It is a rapid process where the virus infects the host cell, takes over the host's machinery, produces new viruses, and then lyses the host cell to release the new viruses. It is a "productive" cycle in terms of new virus production and host cell destruction.
- **Lysogenic Cycle**: In the lysogenic cycle, after the virus inserts its genetic material (provirus or prophage) into the host cell, the viral genetic material integrates into the host cell's genome (in the case of temperate bacteriophages, the phage DNA integrates into the bacterial chromosome; for some animal viruses, the viral DNA may integrate or exist as an episome). The host cell then replicates normally, and the viral genetic material is replicated along with the host cell's DNA during cell division. The virus remains dormant (latent) in this state. The lysogenic cycle can switch to the lytic cycle under certain conditions (like environmental stress to the host cell, e.g., UV radiation or chemical mutagens). To relate to the "Operation Infiltration" illustration (showing virus DNA integrating into bacterial DNA), in the lysogenic cycle, the viral DNA (prophage) is part of the host cell's genome, and the host cell divides, passing on the prophage to daughter cells. In contrast, the lytic cycle is about immediate virus production and host cell lysis.

# Answer:
### Question 10:
- **Common**: Genetic material (DNA/RNA) + capsid (protein coat); some have envelope.
- **Different**: Capsid shape, genetic material type, envelope presence, host range, surface proteins.

### Question 11:
Draw virus/genetic material entering host cell (e.g., phage injecting DNA, animal virus endocytosis/fusion).

### Question 12:
Draw host cell machinery making viral components (transcription/translation of viral genes).

### Question 13:
Draw assembly of new viruses (capsid + genetic material; enveloped viruses budding).

### Question 14:
Draw lysed host cell releasing viruses to infect new host cells.

### Question 15:
Lysogenic: Viral DNA integrates into host genome, host divides (passes prophage), latent until stress triggers lytic cycle. Lytic: Immediate virus production + host lysis.

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Question 15 (Lysogen…

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