Module #4: Cell Structure and function
Viruses: Structure, Replication, and Disease
(Cell structure and Function)
4C: Compare the structures and reproduction of viruses to cells and their role in causing diseases.
Purpose: To reinforce your understanding of the structure of viruses and how they replicate by infecting living cells. The activity also reinforces how viruses can cause disease in plants and animals.
Procedures:
-Define the following terms
-Answer the following questions
-fill in the Venn diagram comparing Viruses and Cell structures.
Terms:
1. Bateriophage
2. Lysis
3. Lysogenic Infection
4. Lytic Infection
5. Replication
6. Capsid
7. Retro-virus (RNA)
8. HIV (explain what type of virus/ what it is/ what type of infection)
Pre-Assessment Question:
9. Why is it necessary for a virus to invade a living cell to make copies of itself?
Venn Diagram
Comparing Virus Structures to cell Structures
10. Scientists consider viruses to be non-living. Based on the information you used to fill in the Venn diagram, would you support or refute this statement? Explain your position in the space below.
11. Some disinfectants claim that they are effective at killing viruses. Does your knowledge of the structures and functions of a virus support or refute this claim? Explain your position in detail below.
12. Locate the lytic infection cycle sheet and the envelope containing the lytic infection cards. Place the cards in the proper sequence on the lytic infection cycle sheet to represent how a virus can infect a living cell and cause the cell to replicate the virus. (this question does not require a written answer)
13. Not all viruses replicate through lytic infection. Some viruses replicate by another method, called lysogenic infection. In this method, as in lytic infection, the virus injects DNA into the host cell, and the virus DNA combines with the DNA of the host cell. This may not cause any damage to the cell for weeks, months, or years. Then the virus DNA begins a process of replication similar to that found in lytic infection.
The human immunodeficiency virus (HIV) replicates by the lysogenic infection method, attacking the cells of our immune system. Why do you think a person infected with HIV has difficulty fighting infections?
14. Locate the model of HIV at this station. Carefully examine the model without removing any of its parts. If a scientist tried to use this model to understand the structure and function of HIV, what limitations would she have?
17. Now return t o the essential question at the beginning of the activity and modify or change your answer if needed.