The Petite Mutations in S

question 40

Multiple Choice

The petite mutations in S. cerevisiae, was discovered by Boris Ephrussi and his colleagues in the late 1940s, result in much smaller colony size, reflecting the defect in the cellular growth rate (Figure 11.15) . Most petite mutations are known to occur on mitochondrial DNA. Which of the following statements offer a logical explanation of the petite phenotype? Select all that apply. (Photo credit: [From Xin Jie Chen and G. Desmond Clark-Walker, Genetics 144: 1445-1454, Fig 1, 1996. © Genetics Society of America. Courtesy of Xin Jie Chen, Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University.])

• A) The defect in the cellular growth comes from an inability to generate enough ATP.
• B) The growth defect is known to come from having excessive copies of mitochondria, resulting in toxicity from excess ATP.
• C) The mutations on the mtDNA can result in deficiency of the enzymes involved in aerobic respiration.
• D) They have no means to make any ATP because of mtDNA defects that affect the normal mitochondrial functions.
• E) The petite mutants only have to rely on anaerobic processes such as fermentation and glycolysis.

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