26. Many clinically relevant mitochondrial diseases are caused by mutations in mitochondrial genes affecting tRNAs. For example, one form of MELAS (mito- chondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) is caused by a point muta- tion in the gene encoding the mitochondrial tRNALeu whose anticodon recognizes the codons 5' UUA and 5' UUG. The mutation makes the aminoacylation of this tRNA inefficient. a. The rate of synthesis of most mitochondrial proteins is either unaffected or slightly decreased in MELAS cells, but one mitochondrial protein called NAD6 is synthesized at only 10% of the normal rate. How is it possible that the translation of this single mito- chondrial protein might be affected specifically? b. Why might the decreased translation of this one pro- tein be responsible for the pathological condition? c. Researchers are currently investigating ways to treat the symptoms of MELAS patients. One strat- egy involves a change to a nuclear gene. What nu- clear gene might the investigators be targeting? (Assume that you can make any desired change to nuclear genes; we will describe methods to alter genomes in Chapter 18.)

26. Many clinically relevant mitochondrial diseases are caused by mutations in mitochondrial genes affecting tRNAs. For example, one form of MELAS (mito- chondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) is caused by a point muta- tion in the gene encoding the mitochondrial tRNALeu whose anticodon recognizes the codons 5' UUA and 5' UUG. The mutation makes the aminoacylation of this tRNA inefficient. a. The rate of synthesis of most mitochondrial proteins is either unaffected or slightly decreased in MELAS cells, but one mitochondrial protein called NAD6 is synthesized at only 10% of the normal rate. How is it possible that the translation of this single mito- chondrial protein might be affected specifically? b. Why might the decreased translation of this one pro- tein be responsible for the pathological condition? c. Researchers are currently investigating ways to treat the symptoms of MELAS patients. One strat- egy involves a change to a nuclear gene. What nu- clear gene might the investigators be targeting? (Assume that you can make any desired change to nuclear genes; we will describe methods to alter genomes in Chapter 18.)

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Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter15: From Dna To Protein

Section: Chapter Questions

Problem 15TYK

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