Myoclonal epilepsy and ragged red fiber disease (MERRF)is a human condition named for the ragged red fibers of skeletal muscle cells and myoclonic epilepsy in affected individuals. People with this disorder have a mutation in a mitochondrial gene for a tRNA, specifically that for lysine. Affected individuals are heteroplastic. Why?
A)Interference with translation slows protein formation and therefore maintenance of mutation-bearing organelles.
B)Having homoplastic organelles would no doubt be lethal due to curtailed translation.
C)Lysine is required in translation of every one of the mitochondrial genes.
D)Mutations of this gene affect individuals before birth.
E)Mutations of this gene are inherited as dominant characteristics.

Question

Quizplus · Accepted Answer

Heteroplasmy refers to the presence of both normal and mutated mitochondrial DNA in the same cell. In MERRF, the mutation affects the mitochondrial gene for a tRNA, specifically that for lysine. Having homoplastic organelles (containing only mutated or only normal mitochondrial DNA) would not be compatible with life due to the importance of mitochondrial function. Therefore, heteroplasmy allows for a distribution of organelles containing both normal and mutated DNA, allowing for some mitochondrial function to still occur despite the mutation.

Myoclonal Epilepsy and Ragged Red Fiber Disease (MERRF)is a Human