Mitochondrial genomes of humans encode about 13 genes involved in oxidative phos
ID: 197296 • Letter: M
Question
Mitochondrial genomes of humans encode about 13 genes involved in oxidative phosphorylation particularly associated with complex I (NADH:lIbiquinone. oxidoreductase complex) and complex IIl (cytochrome C oxidase complex). What affect would loss-of-function mutations to these genes have on the ATP production of the cell? (1pt) Myopathy is a common symptom of mutations associated with mitochondrial genomes - why do you think that is so? (2pts) What affect will beteroplasmy have on the severity of myopathy? (2pts) A child with myopathy was found to have reduced oxidative phosphorylation but no mutations to the Mt DNA. Interestingly, transcription rates were greatly reduced in Mt of the child. What could explain these results? (2pts) a. b. c. d.Explanation / Answer
Complex I catalyzes electron transfer from NADH to ubiquinone, while complex III cytochrome c oxidase plays important role in the respiratory electron transport chain of mitochondria. Mutations in these key enzymes will affect the electron transport chain.
Myopathy which is caused by mitochondrial DNA depletion syndrome, is an inherited condition which causes progressive muscle weakness.
Deleterious heteroplasmic mutations affects the likelihood and severity of the disease phenotype.