Question

Choose the incorrect statement about mitochondria.
A. Has 80S ribosome.
B. Naked circular DNA.
C. ETS on the inner mitochondrial membrane.
D. Powerhouse of the cell.

Answer 1

Hint: Mitochondria are cylindrical or sausage-like and are double-membrane organelles found in the cytoplasm of cells. Mitochondria are small in size and hence not visible underneath the microscope so are stained by an important stain known as Janus Green. They produce ATP which is known as the powerhouse of the cell.

Complete step by step answer: The mitochondria are double membranous structures. They have an outer membrane and the inner membrane dividing its lumen separately into two different compartments, i.e., the outer compartment and the inner compartment. The outer membrane of the mitochondria consists of about chemically 40 percent lipid and about 60 percent proteins while the inner membrane has 80 percent protein and about 20 percent lipids and is known to be rich in cardiolipins. As mitochondria have two membranes, space is divided into two separate chambers which are filled with aqueous fluid- the outer compartment (also known as intermembrane space) and inner compartment (matrix).
•The matrix of mitochondria has a single circular naked DNA molecule, a few RNA molecules are also present along with ribosomes (the 70S) and the components required for the manufacturing of proteins. Thus, Mitochondria has 70S ribosomes and not 80S.

•ETS (Electron transport system) is present on the inner side of the mitochondrial membrane.
•Mitochondria are known to be sites for aerobic respiration since they bring about oxidation of fats, carbs, etc. They produce cellular energy in the form of ATP which is known as the currency of the cell. Therefore, they are called the ‘powerhouse’ of the cell.
So, the correct answer is 'Option A'.

Note: Mitochondria are semi replicating in nature. In order for a new mitochondrion to arise division of pre-existing ones must necessarily occur. They are known to be semi-autonomous cell organelle. They are responsible for synthesizing a few of their proteins.