Viruses and Bacteria Section 18.1 Viruses

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1 Viruses and Bacteria Section 18.1 Viruses Research List three vaccines and the disease that each vaccine prevents. New Vocabulary Use your book to define the following terms. bacteriophage capsid host cell prion viroid virus lysogenic cycle lytic cycle provirus retovirus reverse transcriptase Use the terms at the left to complete the following paragraph. During a a virus takes over a host cell s genetic material and uses its structures and energy to replicate until the host cell bursts. A virus s nucleic acid integrates into the host cell s chromosome, during a. It is then called a. It replicates each time the host cell reproduces. A makes DNA from its RNA using, an enzyme it carries inside its capsid. The viral DNA is then integrated into the host cell s chromosome. 170 Viruses

2 Section 18.1 Viruses (continued) What is a virus? Sketch a model of a virus in the space below. Be sure to label the following parts in your sketch. Capsid Nucleic Acid Envelope Describe how a virus enters a host cell. Viral Replication Cycles Label steps A, B, C, D, and E of a lytic cycle in the figure below. Use the following terms. Assembly Attachment Entry Lysis and Release Replication Nucleic acid Bacterial host cell Bacteriophage A E Attachment Bacterial DNA B Lysis and Release The host cell breaks open and releases new virus particles. Entry The bacteriophage injects its nucleic acid into the bacterial cell. D Assembly New virus particles are assembled. C Replication The host s metabolic machinery makes viral nucleic acid and proteins. Viruses and Bacteria 171

3 Section 18.1 Viruses (continued) Viral Replication Cycles Sequence the steps of a lysogenic cycle. 1. A virus. 2. The viral enters the cell. 3. Viral DNA is. 4. The provirus replicates along the host cell s chromosome. Cancer and Viruses, and Origin of Viruses Explain the role of reverse transcriptase. Create one review question relating to the link between viruses and cancer and one review question relating to the origin of viruses. Include your answer to each question. 1. Question: Answer: 2. Question: Asnwer: 172 Viruses

4 Viruses and Bacteria Section18.2 Archaebacteria and Eubacteria Scan Section 2 of your book. Write two facts you discovered as you scanned the section. 1. New Vocabulary binary fission 2. Use your book to define each term. chemosynthesis conjugation endospore nitrogen fixation obligate aerobe obligate anaerobe toxin Viruses and Bacteria 173

5 Section18.2 Archaebacteria and Eubacteria (continued) Diversity of Prokaryotes Describe Give a general description of the three types of environments where archaebacteria live. With each general description, also provide one specific example of the environment Organize information about the three types of eubacteria by completing the graphic organizer below. Label the three types, and describe how they obtain food. type: type: type: What is a bacterium? food: food: food source: Draw and label a bacterial cell in the space below. Use the figure in your book for help. Be sure to include the following parts. capsule flagellum plasma membrane cell wall pilus plasmid chromosome 174 Archaebacteria and Eubacteria

6 Section18.2 Archaebacteria and Eubacteria (continued) What is a bacterium? Adaptations in Bacteria Compare bacterial reproduction by completing the table below. Binary Fission Conjugation Type of asexual sexual Reproduction How It Occurs a bacterium makes one bacterium a copy of its transfers chromosome and chromosomes to splits in two another bacterium through pili Description of Cells genetically identical new genetic Produced combination Summarize information about endospores by answering the questions below. What are they? How do they germinate? The Importance of Bacteria How can they cause problems for humans? List five ways that bacteria are helpful to humans SYNTHESIZE Assess whether bacteria are more harmful than helpful to humans. Defend your answer. Viruses and Bacteria 175