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Biology Chapter 18 Objectives

Biology Chapter 18 Objectives - Chapter 18 The Genetics of...

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Chapter 18 The Genetics of Viruses The Connection Between Genes and Proteins 1. Adolf Mayer, Dimitri Ivanowsky, Martinus Beijerinck, and Wendell Stanley all helped to discover viruses. 2. Viruses are made up of nucleic acid, DNA or RNA, and are enclosed in a protein coat, the capsid, and sometimes further wrapped in a membranous envelope. The individual protein subunits making the capsid are called capsomeres. Although diverse in size and shape, viruses have common structural features. 3. Viruses are intracellular parasites because they mess up the cell. They attach to it and make it so the cell will make more viruses. 4. The virus identifies a host cell by the cell’s receptor molecules. 5. Bacteria use restriction enzymes against phages. 6. Lytic reproductive cycle is when the virus uses the cell to produce the virus DNA inside the cell then the new viruses are made when they leave the cell. In the lysogenic cycle, the virus enters the cells and makes copies of itself in the cell. Then the new viruses assemble in the cell and lyse. 7. The glycoproteins on the viral envelope bind to specific receptor molecules on the host cells, promoting viral entry into the cell. The capsid and viral genome enter the cell. Digestion of the capsid by cellular enzymes releases the viral genome. The viral genome functions as a template for synthesis of complementary RNA strands by a viral enzyme. New copies of viral genome RNA are made using complementary RNA strands as templates. Each new virus buds from the cell. Its envelope is studded with viral glycoproteins embedded in membrane that are derived from the ER. A capsid assembles around each viral genome molecule. Vesicles transport envelope glycoproteins to the plasma membrane. Complementary RNA strands also function as mRNA, which are translated into both capsid proteins and glycoproteins for the viral envelope.
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