Question

Select the correct statement regarding mitochondria.
A) Mitochondria show a great degree of variability in their shape and size but their number remains constant per cell.
B) Outer membrane is composed of 80% proteins and 20% lipids.
C) The enzymes and electrons carried for the formation of ATP are present only in the inner membrane.
D) These are miniature biochemical factories where proteins and fats are completely reduced.

Answer 1

Hint: Eukaryotic cells have well-organized membrane-bound nucleus or organelles. Mitochondria is the cell organelle in eukaryotic cells. A mitochondrial is a double membrane-bound structure with an outer membrane and an inner membrane. It divides the lumen into two aqueous compartments: outer compartment and inner compartment (matrix).

Complete answer:
Now, to answer this question we have to look at all the options and find the correct one.
A) The number, shape and size of mitochondria per cell are variables depending on the physiological activities. It is sausage or cylindrical in shape having a diameter of 0.2-1.0 µm and length 1.0-4.1 µm.
B) Inner membrane forms a number of infoldings (cristae) towards the matrix and they increase the surface area. In the inner mitochondrial membrane, the ratio of protein to lipid is 80:20 percent but in the outer membrane, the ratio is 50:50.
C) Mitochondria are the sites of aerobic respiration. They produce energy in the form of ATP so they are called the powerhouses of the cell. So, the enzymes and electrons are present in the inner membrane.
D) The 2 membranes have their own specific enzymes associated with mitochondrial function. Matrix possesses a circular DNA ribosome (70s) and components for protein synthesis. They are the sites for aerobic respiration. They produce cellular energy.

Thus the correct answer is option ‘C’.

Note: The mitochondria divide by the asexual mode of reproduction named fission. Human mitochondria have its own genome and has circular DNA. One mitochondrial contains 2 to 10 copies of its DNA. ATP stands for Adenosine Triphosphate. In 1898 Carl Benda coined the term mitochondria and it has a lot of features common with bacteria.