5. To begin to control a disease caused by a protein deficiency, the passage suggests that a promising experimental treatment would be to administer a drug that would reduce

　　(A) only the degradation rate for the mRNA of the protein involved

　　(B) only the synthesis rate for the mRNA of the protein involved

　　(C) both the synthesis and degradation rates for the mRNA of the protein involved

　　(D) the incidence of errors in the transcription of mRNA's from genetic nucleotide sequences

　　(E) the rate of activity of ribosomes in the cytoplasm of most cells

　　6. According to the passage, which of the following best describes the current view on the relationship between the synthesis and the degradation of mRNA in regulating protein synthesis?

　　(A) Biologists have recently become convinced that the ribosome controls the rates of synthesis and degradation of mRNA.

　　(B) There is no consensus among biologists as to the significance of mRNA degradation in regulating protein synthesis.

　　(C) The concept of mRNA degradation is so new that most biologists still believe that the vital role in protein regulation belongs to mRNA synthesis.

　　(D) Degradation of mRNA is now considered to be the key process and mRNA synthesis is no longer believed to play a significant role.

　　(E) Degradation of mRNA is now considered to be as important as mRNA synthesis has been, and still is, believed to be.

　　7. According to the passage, which of the following can happen when protein synthesis is not appropriately regulated?
　(A) Diabetes can result from errors that occur when the ribosomes translate mRNA into protein.

　　(B) Cancer can result from an excess of certain proteins and diabetes can result from an insulin deficiency.

　　(C) A deficiency of red blood cells can occur if bone marrow cells produce too much hemoglobin.

　　(D) Cancer can be caused by excessively rapid degradation of certain amino acids in the cytoplasm of cells.

　　(E) Excessive synthesis of one protein can trigger increased degradation of mRNA's for other proteins and create severe protein imbalances.

　　8. The passage suggests that a biologist who detected high levels of two proteins in a certain type of cell would be likely to consider which of the following as a possible explanation?

　　(A) The rate of mRNA degradation for one of the proteins increases as this type of cell develops a more specialized function.

　　(B) The two proteins are most likely constituents of a complex substance supporting the cells' specialized function.

　　(C) The cells are likely to proliferate abnormally and possibly become cancerous due to the levels of these proteins.

　　(D) The mRNA's for both proteins are being degraded at a low rate in that type of cell.

　　(E) The mRNA's for the two proteins are being synthesized at identical rates in that type of cell.