Download 4C Viruses

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Review
B.4C: Viruses
B.4C: Compare the structures of viruses to cells, describe viral reproduction, and describe
the role of viruses in causing diseases such as human immunodeficiency virus (HIV) and
influenza.
✪ Readiness Standard
1. A virus is an obligate parasite that can only replicate inside another cell. Viruses
are not living because they must live inside another cell and use the host’s
machinery to reproduce and synthesize proteins. A virus consists of nucleic acids
(DNA or RNA) in a capsid (protein coat) and is much smaller than a cell.
2. Viruses reproduce either by using the host cell’s machinery to replicate, causing it
to burst (lytic cycle), or by incorporating itself in specific areas of host DNA
(lysogenic cycle).
3. Viruses infect cells and can cause disease. Some animal viruses can transform a
cell to a cancer cell and can genetically alter a cell to initiate the formation of a
tumor. Bacteriophages are viruses that infect prokaryotic cells. Retroviruses contain
reverse transcriptase that allows them to transcribe RNA into DNA.
Vocabulary
antibiotic, bacteriophage, capsid, chicken pox, genetic material, hepatitis C, host,
Human Immunodeficiency Virus (HIV), immunization, influenza, lysogenic cycle, lytic
cycle, measles, mumps, passive immunity, pathogen prion, retrovirus, rubella, small
pox, t-cell, toxin, vaccine, vector, virus
Fundamental Questions
Use the Key Concepts information as well as the information in your Stemscopedia
beginning on page 17 to answer the fundamental questions below.
1. How are viruses and cells similar?
2. Why is a virus not a cell?
3. Why does a virus have to use a cell to replicate?
4. What are the various types of viruses?
5. How does a virus cause disease?
Analysis
Complete the following in the space provided.
1) Write a summary to describe the structure of a virus.
2) Make a graphic organizer that compares the structures of a virus and of a cell.
3) Draw a model of the structure of a virus.
4) Explain how viruses reproduce.
5) Diagram the cycles of viral reproduction.
6) Write a summary describing how some diseases are caused by viruses.