Viruses and Bacteria Study Guide (biology)
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Viruses
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Composed of nucleic acids enclosed in a protein coat and are smaller than the smallest bacterium. Can’t carry out respiration, grow, or develop, but can replicate. Has an inner core of nucleic acid, either RNA or DNA, and an outer protein coat.
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Host Cell
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A cell in which a virus replicates
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Bacteriophage
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A virus that infects a bacterium
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Capsid
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An outer protein coat; the arrangement of proteins that determines a viruses shape.
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Replicate
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Before a virus can ___________ it must enter a host cell
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Protein
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Each virus has a specifically shaped attachment protein (can usually attach to only a few kinds of cells)
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Viral Replication Cycle
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Once attached to the plasma membrane of the host cell, the virus enters the cell and takes over its metabolism
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Lytic cycle
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The host cell uses its own enzymes, raw materials, and energy to make copies of viral genes that along with viral proteins are assembled into new viruses, which burst from the host cell, killing it.
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Lysogenic Cycle
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Does not immediately take over the cell; viral DNA is integrated into the host chromosome
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Provirus
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Viral DNA that is integrated into the host cells chromosome
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Prions
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Composed of proteins; no nucleic acid to carry genetic information
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Retroviruses
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Convert their RNA to DNA when RNA experiences reverse transcriptase to help produce double stranded DNA
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Viroids
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Composed of single circular strand of RNA with no protein coat
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Archaebacteria and Bacteria
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Cells walls and lipids in their plasma differ
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Methane gas producing archaebacteria
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Live in oxygen free environments
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Archaebacterium
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Lives only in water with high concentrations of salt
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Anaerobic archaebacterium
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Live in the hot acidic waters
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Eubacteria
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Prokaryotes that live in more hospitable places; vary in nutritional needs
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Saprophytes
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Organisms that feed on dead organisms or organic wastes
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Photosynthetic autotrophs
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Live in places with sunlight to make organic molecules for food (Cyanobacteria)
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Capsule
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Sticky gelatin around the cell wall (more likely to cause a disease than one without a capsule)
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Bacteria
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Live in hypotonic environments (always trying to take water in)
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Binary fission
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Bacteria reproduce asexually
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Conjugation
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One bacterium transfers all or part of its chromosome to another cell through or on a bridge like structure called a pills (pili) that connects the two cells