Question

Extranuclear inheritance is due to presence of genes in-
A. Mitochondria and chloroplasts
B. Nucleus and mitochondria
C. Nucleus and chloroplasts
D. Endoplasmic reticulum and mitochondria

Answer 1

Hint: As the name suggests, the inheritance is extranuclear means it is the transmission of genes that occur outside the nucleus. Mostly, it is found in eukaryotes and is as a rule known to occur in cytoplasmic organelles or from cellular parasites like viruses or bacteria. It is also defined as a non-mendelian inheritance.

Complete answer: Chloroplasts and mitochondria are semi-autonomous cell-organelles possessing their own DNA and proteins. In animals, an individual gets mitochondria and mitochondrial genes from its mother because the middle piece of a sperm that contains mitochondria does not enter the egg during fertilization.
This inheritance outline of mitochondrial genes is known as the uniparental inheritance or extranuclear inheritance or maternal inheritance.
The gene which is present in the nucleus is not considered as the extranuclear inheritance DNA. The endoplasmic reticulum is devoid of extranuclear inheritance DNA.
Cytoplasmic factors are located in the cytoplasm and it is independent, self-replicating nucleic acids, which differ from chromosomal genes only by their location inside the cell, and have their own nucleotide sequences such as Mitochondria, Chloroplast, and Plasmid. It is also commonly referred to as non-Mendelian, non-chromosomal extra-nuclear inheritance.
So, the correct answer is “Option A”.

Note:
In extranuclear inheritance, only one parent contributes organellar DNA to the offspring. Maternal inheritance of human mitochondria is a famous example of uniparental gene transmission. The mother's mitochondria are transferred to the offspring when fertilization occurs through the egg. The machinery of uniparental inheritance from species to species varies to a great extent and is somewhat complicated.