Why is the mitochondrial disease MELAS, which results in stroke-like episodes in addition to encephalopathy and lactic acidosis, only transmitted by a motherand not by an affected father?
A)The mitochondria are in the cytoplasm, and virtually all the cytoplasm comes from the egg and is thus maternally inherited.
B)This is an X-linked-recessive condition, so the father can only transmit the gene to his daughters and not to his sons.
C)Mitochondria are in the cytoplasm and are not equally divided during gamete formation in meiosis.
D)MELAS reduces the percentage of Y-carrying sperm in affected males.

Question

Quizplus · Accepted Answer

Mitochondria are in the cytoplasm only. A sperm does not contain cytoplasm. Thus, when an egg is fertilized, all the mitochondria in it are maternally derived, regardless of whether the zygote is a male or a female.

Why Is the Mitochondrial Disease MELAS, Which Results in Stroke-Like