In cell biology, the cytoplasm is the material within a living cell, excluding the cell nucleus. It comprises cytosol and the organelles – the cell's internal sub-structures. All of the contents of the cells of prokaryotic organisms (such as bacteria, which lack a cell nucleus) are contained within the cytoplasm. <span>The mitochondrion is a double membrane-bound organelle found in all eukaryotic organisms. Some cells in some multicellular organisms may, however, lack them.</span>
The first stage of cellular respiration occurs in the cytoplasm. This is where glucose is broken down into smaller molecules. A small amount of energy is also released. The second stage occurs in the mitochondrion. This is where the small molecules combine with oxygen to produce water, carbon dioxide, and a large amount of energy.
