Lesson 3.6 Viruses

3.6.1 Introduction to Viruses

Opening Activity: part A

1. On a half sheet of paper or a note card, answer the following questions:

 a. Are viruses living organisms? Why or why not?

 b. What do viruses do?

 c. Draw what you think a virus looks like.

 d. List any names of viruses that you are aware of.

 e. Share your work as directed by your instructor.

Opening Activity: Part B

 Use the diagrams in figure 3.6.1 to answer the questions that follow.

^[1]

 (a)

^[2]

Structure of Bacteriophage T4.

 (b)

1. Head
2. Tail
3. Nucleic acid
4. Capsid
5. Collar
6. Sheath
7. Tail fiber
8. Spikes
9. Baseplate

^[3]

 (c )

Diagram (a) represents the structure of the tobacco mosaic virus, which infects tobacco plant cells. 

Diagram (b) represents the structure of the bacteriophage T4 virus, which infects a specific type of bacterium.

Diagram (c) represents the structure of the cytomegalovirus, which infects humans.

1. Choose ONE of the diagrams and answer each of the following questions:

 . Describe how this virus’s structure is:

 a. different from a prokaryotic cell.

 b. similar to a prokaryotic cell.

 c. different from an eukaryotic cell

 d. similar to an eukaryotic cell

2. Share your work as directed by your instructor.

Introduction to viruses

Viruses are considered by scientists to be non-living, in part due to their structure and inability to reproduce independent of a living host cell. They can infect and cause disease in a variety of living cells including plant cells, animal cells, and bacteria. As you saw in the opening activity, viruses exist in different forms. Their structure and type of nucleic acid form the basis for their classification.

While most often associated with causing disease, viruses can also be genetically engineered to deliver specific genes to cells, as demonstrated by research investigating possible methods of gene therapy to treat human genetic disorders.