Question

Describe the structure of mitochondria with the help of a diagram?

Answer 1

Hint: Mitochondria are cylindrical or sausage shaped double membrane organelles present in the cytoplasm. They are not easily visible under the microscope and they are stained by a vital stain Janus green.

Complete answer:

Mitochondria are also called the powerhouse of the cell. They show a great degree of variability in their shape, size and number. A typical mitochondrion having a diameter of 0.2-1.0 µm and length of 1.0-4.1 µm. Mitochondria is surrounded by outer membranes and inner membranes. The outer membrane is smooth and forms the continuous limiting boundary of the mitochondria whereas the inner membrane forms a number of infoldings called the cristae.

Outer membrane is chemically 40% lipid and 60% proteins and the inner membrane has 80% protein and 20% lipids and it is rich in cardiolipins. Due to the presence of two membranes, the organelle is divided into two distinct chambers filled with aqueous fluid- outer compartment (intermembrane space) or inner compartment (matrix).

The matrix contains a single circular dsDNA molecule, a few RNA molecules and 70S ribosomes.
Functions of the mitochondria:
- Mitochondria are the main site of aerobic respiration.
- They bring about the oxidation of carbohydrates, proteins and β-oxidation of fats.
- The energy (ATP) produced in the mitochondria helps to perform various energy requiring processes of the cells like muscle contraction, nerve impulse conduction etc.

Note: Mitochondria are semi replicating organelles. New mitochondria arise by the division of pre-existing ones. They are the semi-autonomous cell organelle. They are capable of synthesizing some of their proteins.