AP BIOLOGY Cells Activity #6 VIRUSES LIFE OF A VIRUS ANATOMY OF A VIRUS. Cell Activity #6 Page 1 of 9

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1 AP BIOLOGY Cells Activity #6 LIFE OF A VIRUS VIRUSES ANATOMY OF A VIRUS Cell Activity #6 Page 1 of 9

2 REPLICATION CYCLES FOR DNA VIRUSES LYTIC CYCLE LYSOGENIC CYCLE Cell Activity #6 Page 2 of 9

3 RNA VIRUSES Cell Activity #6 Page 3 of 9

4 USE THE TEXTBOOK (CHAPTER 19) TO ANSWER THE FOLLOWING QUESTIONS. 1. Viruses can vary with respect to all of the following characteristics except. (Concept 19.1) a. DNA or RNA as the genetic material b. the presence or absence of metabolic machinery c. single- or double-stranded nucleic acids d. the presence or absence of a membranous envelope e. the type of host cell it can infect 2. A microbiologist analyzes chemicals obtained from an enveloped RNA virus that infects monkeys. He finds that the viral envelope contains a protein characteristic of monkey cells. Which of the following is the most likely explanation? (Concept 19.1) a. The viral envelope forms as the virus leaves the host cell. b. The virus forced the monkey cell to make proteins for its envelope. c. The virus is a prophage. d. Its presence is a result of the monkey's immunological response. e. The virus fools its host by mimicking its proteins. 3. Which of the following, if any, may be a component of a virus? (Concept 19.1) a. protein b. double-stranded (ds) DNA c. phospholipid bilayer d. single-stranded (ss) RNA e. all of the above 4. Viruses that infect bacteria are called. (Concept 19.1) a. bacterioviruses b. bacteriophages c. capsomeres d. proviruses e. retroviruses Cell Activity #6 Page 4 of 9

5 5. HIV, the virus that causes AIDS, only infects certain cells within the immune system. This is because. (Concept 19.2) a. the virus is not very mobile within the body and only comes into contact with a limited number of immune cells b. other cells produce toxins that destroy the virus before infection can take place c. the virus binds to specific receptors that are only present on certain immune cells d. the virus gets into all cells, but the viral RNA is immediately destroyed in all but a small number of immune system cells e. infection requires the presence of a specific DNA sequence that is only present in the genome of certain immune system cells 6. Cancer cells often have protein receptor molecules on their surfaces that differ from those on normal body cells. Given this fact, how might viruses be used to treat cancer? (Concept 19.2) a. Viruses are pathogenic and will infect the host. This treatment will not work. b. Viruses could be used to carry genes exclusively to the normal body cells. These genes could encode proteins that would help destroy the cancer cells. c. Viruses could be engineered to infect only cancer cells by altering viral surface proteins to recognize only the receptors on cancer cells. d. Viruses sometimes cause cancer. This is a bad idea. e. Viruses could be engineered to attach to the surface receptors on cancer cells to alert the immune system to the presence of cancer. 7. Why are phages useful in treating bacterial infections in humans? (Concept 19.2) a. Because of their host specificity, they only attack bacteria. They do not affect eukaryotic cells. b. Because of their specificity, a phage can be used that will only infect the pathogenic bacteria, leaving helpful bacteria alone. c. Because phages are free to evolve, bacteria are less likely to develop a lasting resistance to them. d. They are not useful, and the practice has been banned in all countries. e. The first three answers are correct. 8. Which of the following can a virus do without a host cell? (Concept 19.2) a. synthesize proteins b. produce ATP for energy c. transcribe DNA d. produce nucleotides for use in replication and transcription e. none of the above 9. When a virus infects an E. coli cell, what part of the virus enters the bacterial cytoplasm? (Concept 19.2) a. the entire virus b. only the nucleic acid c. the protein capsid and enclosed nucleic acid d. the tail fibers e. the protein capsid only Cell Activity #6 Page 5 of 9

6 10. The phage reproductive cycle that kills the bacterial host cell is a cycle, and a phage that always reproduces this way is a phage. (Concept 19.2) a. lytic; virulent b. lytic; lysogenic c. lysogenic; temperate d. virulent; lytic e. lysogenic; virulent 11. In the lytic life cycle of phages. (Concept 19.2) a. the cell typically dies, releasing many copies of the virus b. the viral capsid is assembled according to the genetic information of the bacterium c. the entire phage is taken into the bacterium d. DNA replication is not part of the life cycle e. phage DNA is incorporated into the host cell's genome 12. Restriction enzymes help defend bacteria against viral infections by. (Concept 19.2) a. preventing the binding of the virus to the cell surface b. preventing entry of the viral DNA into the cell c. cutting viral DNA once it has entered the cell d. preventing the synthesis of viral capsomeres in the cell e. preventing integration of the viral genome into the host chromosome 13. A phage that inserts itself into the host DNA is called. (Concept 19.2) a. a bud b. lysogenic c. a bacteriophage d. semipermeable e. a capsomere 14. A prophage is a(n). (Concept 19.2) a. emerging virus b. virus that infects bacteria c. type of retrovirus d. prion that has been integrated into a bacterial cell's chromosome e. viral genome that has been incorporated into a bacterial cell's chromosome 15. In the lysogenic cycle of phages. (Concept 19.2) a. the nucleic acid core of the phage is all that enters the host cell b. only a small number of the viral genes are expressed c. the viral nucleic acid inserts itself into the host chromosome d. the viral nucleic acid is replicated along with the host DNA e. all of the above Cell Activity #6 Page 6 of 9

7 16. What is the origin of the phospholipid membrane that envelops many animal viruses? (Concept 19.2) a. It is produced by viral enzymes and contains only viral proteins and phospholipids. b. It is assembled from free phospholipids floating in the cell's cytoplasm. c. It is "stolen" from the host cell and contains only host cell proteins and phospholipids. d. It is assembled in the ER based on signals sent out by the viral genome. e. It is "stolen" from the host cell, but it contains some proteins encoded by the viral genome. 17. Why can flare-ups of herpesvirus infection recur throughout a person's life? (Concept 19.2) a. The herpesvirus becomes a prophage during the lysogenic cycle of the infection, so the viral genome is recombined with the host DNA. b. Herpesvirus can leave its DNA behind as minichromosomes in nerve cell nuclei. Stress can trigger another round of virus production, producing characteristic blisters and sores. c. Herpesvirus is very common in the environment, so it is easy for a person to become reinfected. d. Herpesvirus may cloak itself in a cell's nuclear envelope, making it very difficult for the immune system to recognize. e. The herpesvirus always kills its host cell when it leaves. Cycles of cell death cause the recurring flare-ups. 18. How do retroviruses, such as HIV, differ from other viruses? (Concept 19.2) a. They have much simpler reproductive cycles than other RNA viruses. b. They contain DNA that is used as a template to make RNA. c. They can reproduce only inside living cells. d. They contain nucleic acids that code for proteins. e. They contain the enzyme reverse transcriptase. 19. Reverse transcription, carried out by retroviruses, is the process by which. (Concept 19.2) a. DNA information is copied into RNA b. RNA information is copied into DNA c. RNA information is "read" to form a protein molecule d. DNA is duplicated e. information is copied from a protein molecule into RNA 20. Which statement below is a correct comparison of a "regular" RNA virus and a RNA retrovirus? (Concept 19.2) a. Only the regular RNA virus performs transcription. b. Only the RNA retrovirus performs translation. c. Only the regular RNA virus produces DNA from an RNA template. d. Only RNA retroviruses produce DNA using DNA replicase. e. Both produce protein coats via translation of mrna. Cell Activity #6 Page 7 of 9

8 21. When comparing DNA and RNA viruses, which mutate more quickly, and why? (Concept 19.2) a. RNA viruses because no proofreading is done on RNA molecules. b. They all mutate at the same rate. c. DNA viruses because they usually have larger genomes and thus more loci for mutations to occur. d. DNA viruses because the host cell's proofreading enzymes do not work on viral DNA. e. RNA viruses because RNA is single-stranded and thus more prone to mutations. 22. The symptoms of a viral infection in a person can be caused by. (Concept 19.3) a. the death of infected cells b. the reaction of the individual's immune system to the infection c. the production of toxins by infected cells d. toxic viral components, such as envelope proteins e. all of the above 23. Vaccines for viral diseases are and help prevent infection by. (Concept 19.3) a. harmless derivatives of pathogenic viruses; stimulating the immune system to mount a defense against the actual pathogen b. nucleoside inhibitors; inhibiting the replication of the viral genome c. protease inhibitors; preventing synthesis of envelope proteins d. antibiotic formulations; specifically killing infected cells e. antibiotic formulations; killing bacteria that assist viruses in infecting animal cells 24. Emerging viruses can originate from which of the following sources? (Concept 19.3) a. animal viruses b. the mutation of existing human viruses c. viruses previously confined to small, isolated populations that can now spread due to technological or social changes such as the development of affordable international travel d. all of the above e. none of the above 25. What is the function of hemagglutinin in the influenza virus? (Concept 19.3) a. Hemagglutinin is the name of the reverse transcriptase enzyme in the influenza virus. b. Hemagglutinin helps release new viruses from infected cells. c. Hemagglutinin is part of the protein capsid of the influenza virus. d. Hemagglutinin is the protein that helps the influenza virus attach to host cells. e. Hemagglutinin is involved in assembling the membrane envelope that the virus uses as a cloak when it leaves an infected cell. 26. Birds act as a natural for the influenza virus.( Concept 19.3) a. defense; A b. reservoir; C c. buffer; B d. reservoir; A e. pandemic; B Cell Activity #6 Page 8 of 9

9 27. Which of the following is an example of vertical transmission of a virus in plants? (Concept 19.3) a. Viral particles are carried by the wind from one plant to another. b. Viral particles are carried from one plant to another by a pair of pruning shears. c. Two neighboring plants touch each other, allowing viruses present in one plant to infect the other plant. d. An infected plant produces seeds that contain the virus, giving rise to infected progeny. e. all of the above 28. Plant viruses spread throughout the plant by way of. (Concept 19.3) a. chloroplasts b. plasmodesmata c. central vacuoles d. the lymphatic system e. vertical transmission 29. Circular RNA molecules that function like a virus in plants are termed. (Concept 19.3) a. rhabdovirus b. viroid c. retrovirus d. prion e. none of the above 30. Prions are that are thought to cause disease by. (Concept 19.3) a. abnormally shaped proteins; inducing similar but normally shaped proteins in the brain to adopt the abnormal form b. RNA molecules; encoding toxic proteins c. mutant DNA molecules; encoding toxic proteins d. an abnormal type of capsid; dramatically enhancing the rate of viral infection e. DNA molecules; jumping around the genome and mutating genes Cell Activity #6 Page 9 of 9