Viruses and Bacteria

Name Date Reinforcement and Study Guide Chapter 18 Class Viruses and Bacteria For each item in Column A, write the letter of the matching item in Column B. Column A Column B C ____________ 1. Genetic material of a virus a. virus E ____________ 2. Where a virus attaches to a host cell b. T4 phage A ____________ 3. Nonliving particle that replicates inside a living cell c. DNA or RNA D ____________ 4. A virus’s protein coat d. capsid 5. Interlocks with a molecular shape in a host cell’s plasma membrane e. receptor site H ____________ F ____________ 6. Layer that surrounds the capsid of some viruses B ____________ 7. A virus that infects E. coli bacteria G ____________ 8. A cell in which a virus replicates f. envelope g. host h. attachment protein In your textbook, read about viral replication cycles. Complete the table by checking the correct column for each statement. Statement 9. Viral genes are expressed immediately after the virus infects the host cell. 10. Many new viruses are assembled. 11. This cycle is preceded by a virus entering a host cell. 12. Viral DNA is integrated into the host cell’s chromosome. 13. Viruses are released from the host cell by lysis or exocytosis. 14. Reverse transcriptase is used to make DNA from the RNA of a retrovirus. 15. A provirus is replicated along with the host cell’s chromosome. Lytic Cycle Lysogenic Cycle Name Date Chapter 18 Viruses and Bacteria, continued Class Reinforcement and Study Guide Use each of the terms below just once to complete the passage. DNA white blood cells lysogenic lytic AIDS proviruses lysogenic Many disease-causing viruses have both lytic and (16) __________________ cycles. For example, white blood cells , the viruses enter a lysogenic cycle. Their genetic when HIVs infect (17) ______________________ DNA of the white blood cells, forming material becomes incorporated into the (18) __________________ proviruses (19) __________________ . When this happens, the white blood cells still function normally, and the lytic cycle, killing person may not appear ill. Eventually, the proviruses enter a (20) __________________ the white blood cells. As a result, the person loses the ability to fight diseases and develops AIDS (21) __________________ . In your textbook, read about viruses and cancer, plant viruses, and the origin of viruses. If the statement is true, write true. If it is not, rewrite the italicized part to make it true. True ____________________ 22. Some viruses can change normal cells to tumor cells. True ____________________ 23. Retroviruses and the papilloma virus, which causes hepatitis B, are examples of tumor viruses. False 24. All plant viruses cause diseases in plants. ____________________ Not all plant viruses cause diseases in plants. True 25. The first virus ever identified was the plant virus called tobacco mosaic virus. ____________________ False ____________________ 26. The patterns of color in some flowers are caused by tumor viruses. The patterns of color in some flowers are not caused by tumor viruses. True ____________________ 27. Tumor viruses contain genes that are found in normal cells. False ____________________ 28. Scientists think viruses originated from their host cells. *Scientists think viruses originated from *host cells rather than the *host cells themselves.