Why is the synthesis of mRNA a central issue for all viruses? How do different types of viruses achieve this goal?
What will be an ideal response?
One way in which a virus gains control of a cell is to direct the synthesis of new viral proteins, which include such molecules as enzymes. To do this, however, the virus must provide the cell with mRNA for the production of such proteins. Viruses can achieve this goal in one of three basic ways: (1 ) they can import mRNA into the cell in the form of the viral genome; (2 ) they can allow the cell to make viral mRNA through normal cellular genetic processes by providing the cell with viral DNA; or (3 ) they can use unique mechanisms to convert their genomes into a form suitable for protein production. An example of the first type of virus is the +ssRNA virus; this type of genome essentially mimics the mRNA found in the cell. An example of the second type is the DNA virus, either ds or ss, which can take advantage of normal cellular processes to produce mRNA. An example of the third type is the -ssRNA virus, which uses a novel enzyme called RNA-dependent RNA transcriptase to convert its genome into +ssRNA, which can then be used for protein synthesis as in the first example.
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Which of the following is false about marine plants?
a. They are common in protected bays. b. They have xylem and phloem tissues. c. They are found only in tropical areas. d. They produce seeds.
All of the following are reproductive structures found in some fungi except
A. mycorrhiza. B. basidium. C. ascus. D. conidia. E. sporangiophore.
Which of the following does not utilize active transport?
A. concentrating iodine ions in the thyroid gland B. absorbing sugar in the gut C. movement of sodium and potassium in nerve cells D. movement of oxygen from the lungs into the blood E. water homeostasis in the kidneys
Membrane structure is made of ______________.
Fill in the blank(s) with the appropriate word(s).