Question

The mitochondrial DNA differs from the nuclear DNA because
A. Being linear
B. Having $A=T$ and C$\equiv$T
C. Lack of binding histones
D. Being highly twisted

Answer 1

Hint: Mitochondria is the powerhouse of the cell that comprises a small circular chromosome consisting of DNA. DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Complete answer:
The major difference between mitochondrial DNA and nuclear DNA are as follows;
- Mitochondrial DNA consists of the DNA in mitochondria whereas nuclear DNA is the cells entire genome including mDNA.
- Mitochondrial DNA is double stranded and circular whereas nuclear DNA is double stranded and linear.
- mDNA is not surrounded by a nuclear envelope but nuclear DNA is.
- mDNA is not packed with histone protein where aa nuclear DNA is.
- mDNA lacks introns but nuclear DNA has both introns and exons.
- mDNA is maternally inherited, nuclear DNA is equally inherited by both parents.
Hence the right answer is option ‘C. Lack of binding histones’.

Note: Mitochondrial DNA comprises 37 genes encoding 13 proteins, 22 tRNAs and 2 rRNAs. Mitochondria is the powerhouse of the cell that comprises a small circular chromosome consisting of DNA.