Cell Structure and Function
Viruses: Structure, Replication, and Disease
Student Pages
Purpose
The purpose of this station is to reinforce your understanding of the structure of viruses and how they replicate by infecting living cells. This activity also reinforces understanding of how viruses can cause disease in plants and animals.
Before You Begin…
Look over the Station Information sheet and make sure that all the items it lists are present at the station. If you notice a problem, notify the teacher immediately.
Materials
Station Information sheet Model of HIV
Structures of Viruses and Cells sheet Lytic Infection Cycle sheet
Lytic Infection cards
Activities and Questions
Essential Question
Why is it necessary for a virus to invade a living cell to make copies of itself?
Discuss the essential question with your teammate(s) and record your answer.
1. Locate the Structures of Viruses and Cells sheet at this station. Carefully examine the structures of the plant cell, animal cell, bacteriophage virus, and influenza virus. Then fill in the Comparing Virus Structures to Cell Structures Venn diagram below.
Comparing Virus Structures to Cell Structures
Structures found in a virus Structures found in a living cell
Structures found in a virus and a living cell
2. Scientists consider viruses to be nonliving. 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.
3. Some disinfectants, like the one pictured below, 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.
Our Product Kills Flu Viruses!
4. 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.
5. 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?
6. Locate the picture 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?
7. Now that you have completed these questions, return to the essential question at the beginning of the activity. Would you like to modify or change your answer? Write any modifications to your answer below.
Practice
1. Viruses can reproduce only under which of the following conditions?
A. When they are outside a living organism
B. When they carry out respiration
C. When they grow or move
D. When they are inside a host cell
2. What is the main function of the projections on the surface of a virus?
A. They aid in respiration
B. They help the virus grow
C. They help the virus invade its host
D. They help the virus digest food molecules
3. What do viruses have in common with living cells? They both…
A. store genetic information in DNA and RNA
B. have chloroplasts
C. use glucose for cellular respiration
D. have endoplasmic reticulum
4. Which of the following statements is true?
A. Viruses have no DNA or RNA B. Viruses use host cells to reproduce
C. Viruses contain no proteins D. Viruses can be killed by antibiotics
6. Which of the following happens as part of both the lytic cycle and the lysogenic cycle?
A. New viruses are made B. The host cell dies
C. The entire virus infects the cell D. The virus injects its nucleic acid into the host cell
7. The lytic cycle involves several steps. Which of the following is the final step of the
lytic cycle.
A. the host cell bursts
B. the virus injects its nucleic acid
C. new viruses begin to be made
D. the viral DNA becomes part of the host cell’s DNA