Question

Rackers particles are found in
A. Chromosome
B. Mitochondria
C. Nucleus
D. Golgi body

Answer 1

These are small round structures present on the folding of the inner membranes of a cell organelle. These folding are known as cristae. These particles have several names, such as Fernandez-Moran particles, Oxysomes, Parsons’s particles, and $F1$ or $F0$ particles.

Complete answer:
The matrix of the mitochondria has numerous folding of the inner membrane of the mitochondria. These folding are known as cristae, which contain hundreds of tennis racket-like particles called Racker particles or Oxysomes. They are also known as $F1$ $-$ $F0$ particles. The base of the particles is known as $F0$ called integral membrane protein and the stalk is known as $F1$ called peripheral membrane protein.
These play an important role in the functioning of the cell as they are considered with energy production. They participate in biochemical processes such as Electron Transport Chain, Oxidative phosphorylation in the synthesis of ATP. This is why mitochondria are known as the powerhouse of the cell. In mitochondria the energy produced inside is also stored.
A mitochondrion has about $104 - 105$ Racker particles or Oxysomes which are present at an interval of $10$ nm. They constitute $15$ percent of the total protein in the inner membrane.

Therefore, the Racker particles are found in the mitochondria, especially on the folding of the inner membrane.

Note:
These Racker particles contain all the necessary enzymes and coenzymes needed in the Electron Transport Chain and assist in the process of cellular respiration. Since they take part in oxidative phosphorylation and ATP production, they are also known as ATP synthase.