What is the difference between maternal inheritance and maternal effect?
Maternal inheritance is encoded by DNA in organelles in the cytoplasm, like chloroplasts and mitochondria, while maternal effect results from RNAs and proteins, encoded by nuclear DNA, and put into oocyte cytoplasm by mom. Mitochondria come from both “parents” in yeast, but only from mom (in the egg) in plants, animals, and even Neurospora. The important distinction is in the inheritance patterns. Since a maternal effect is not inherited (like nuclear and organelle DNA is), the genotype of mom determines the phenotype of all progeny, male and female. With maternal inheritance, the genotype of mom determines genotype of all progeny, male and female, and genotype = phenotype. Basically, the genotype is M for females, and males genotype is nonexistent, as far as gametes go (sperm contribute no mitochondria or chloroplasts).
