Question

Large numbers of mitochondria are found in?
A) Thigh muscles
B) Cardiac muscles
C) Breast bone of bird
D) All of the above

Answer 1

Membrane-bound cell organelles (mitochondrion, singular) are mitochondria which generate most of the chemical energy required to power the biochemical reactions of the cell.

Complete answer:
Using the oxygen available in the cell, mitochondria transform chemical energy from food in the cell into energy in a form that is functional for the host cell. The method is called oxidative phosphorylation, and within mitochondria it occurs.

In the body, mitochondria play various roles, including energy production, generation of reactive oxygen species and signal transduction. Since a high-energy-demand tissue is the myocardium, the muscular wall of the heart, mitochondria play a central role in maintaining optimal cardiac efficiency. Growing evidence indicates that in cardiovascular diseases, deregulated mitochondrial activity plays a causative role.

Mitochondria and ER are intertwined throughout the body and form their own networks of endomembranes. As mitochondria-associated ER membranes (MAMs), the points where mitochondria and ER make physical contact and interact are established. In the control of calcium transfer between the ER and mitochondria, MAMs play a major role. Several neuronal diseases are involved in defective MAMs, including Alzheimer's disease and Parkinson's disease.

They are present in large numbers in the muscles of the thigh, but are much more common in the muscles of the heart, making up 35% of the cardiac muscle volume in the heart.This is exactly why, while other muscles sometimes do, the heart 'never gets tired'.

Thus the correct answer is option (B) Cardiac muscles.

Note: Facts of Mitochondria
i) When required, they can rapidly change shape and travel around the cell.
ii) The mitochondria will replicate as the cell requires more energy by becoming larger and then dividing. iii) Certain mitochondria will die or become inactive if the cell needs less energy.
iv) For some bacteria, mitochondria are very similar. Some scientists believe, for this reason, that they were initially bacteria that were absorbed by more complex cells.