Alleles for genes located on mitochondrial DNA are said to be maternally inherited. What is the reason for this pattern of inheritance?
A) The egg and sperm contribute equal numbers of cytoplasmic organelles to the zygote.
B) The egg contributes virtually all of the cytoplasmic organelles to the zygote.
C) Half of the nuclear chromosomes in the zygote come from the father.
D) Half of the nuclear chromosomes in the zygote come from the mother.
E) All of the nuclear chromosomes in the zygote come from the mother.

Question

Quizplus · Accepted Answer

Mitochondria are only present in the cytoplasm of the egg cell, and not in the sperm. Therefore, during fertilization, the zygote inherits all of its mitochondrial DNA from the egg cell and none from the sperm, resulting in maternally inherited alleles.

Alleles for Genes Located on Mitochondrial DNA Are Said to Be