What is the role of mitochondria in animal cells?

Mitochondria are organelles which provide the energy used up by the cell in respiration, through producing molecules called ATP. Some cells have loads of mitochondria, and other cells have very little. For example, muscle cells, which require a lot of energy to do work, have loads of mitochondria whereas neurons have very few.

Structure of Mitochondria

The mitochondria are perfectly shaped to maximise energy production. They have a normal outer membrane which holds all of the contents of the organelle, and an inner membrane which folds over many times to increase surface area. These are called cristae. The fluid in the middle of the mitochondria is called the matrix.

The increased surface area of the inner membrane allows a lot of chemical reactions to happen at once.

How Do Mitochondria Produce Energy?

The matrix is filled with water and proteins (enzymes). These enzymes take organic molecules produced in the breakdown of food (glucose), such as pyruvate and Acetyl CoA and digest them chemically.

Proteins in the inner membrane and enzymes in the citric acid cycle releases water (H₂O) and carbon dioxide (CO₂) from the breakdown of oxygen (O₂) and glucose (C₆H₁₂O₆).