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Virtual Lab – Viruses

In this lab exercise you will watch animations about viruses and answer questions about them.

• The first animations illustrate the lysogenic and lytic cycles of viruses.
• The second animation shows how different types of viruses enter animal host cells.
• The third animation demonstrates how a bacteriophage infects a bacterial cell.

ANIMATION #1

Click on the links below to watch YouTube animations about the lysogenic and lytic cycles of viruses:

excellent animation of the lytic cycle :

excellent animation of the lysogenic cycle:

Answer the following questions about the animations:

1. Name the parts of a virus:

2. How do viruses reproduce?

3. What happens in the first stage of viral replication?

4. What happens in the second stage of viral replication?

5. What happens to the viral DNA during the lysogenic cycle?

6. The incorporated viral DNA is called a:

7. During the lytic cycle, what does the viral DNA force the host cell to do?

8. What happens after new viruses are assembled inside the host cell?

ANIMATION #2

Click on the link below to watch an animation by McGraw-Hill about the entry of a virus into an animal host cell:

http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter18/animation_quiz_1.html

Answer the following questions about the animation:

1. Name the green molecules embedded in the envelope of the virus, or virion:

2. What do these molecules attach to on the host cell membrane?

3. What does the envelope of the virus fuse with in order to release the viral capsid into the host cell?

4. What is the innermost part of the virus that is released by the protein capsid into the cytoplasm of the host cell?

5. In the second method the host cell’s plasma membrane completely surrounds the virus envelope in a process called:

6. As a result, the virus is temporarily contained within a:

7. Another type of virus is a naked virion, which has no outer:

8. Naked viruses are also taken into the host cell by the process:

ANIMATION #3

Click on the link below to watch an animation by About.com Biology about bacteriophages:

http://biology.about.com/od/virology/a/aa11108a.htm

Read the introductory material, click on Animations A, B, C, D, and E and then answer the following questions about the animation:

1. What is the name for a virus that infects a bacterial cell?

2. What does it have attached to its capsid that helps it attach to the bacterial cell?

3. Where are the host cells receptors located:

4. What substance in the bacterial cell wall is broken down by the bacteriophages in order to release them from the cell?