2.4. Mitochondria

While chloroplasts synthesize carbohydrates, mitochondria respire the carbohydrates to generate energy in the form of universal “energy currency” Adenosine triphosphate (ATP). Thus, photosynthesis and respiration are, in principle, opposite chemical reactions. 

Structurally, mitochondria are double-walled organelles as seen in the interactive image on the right. There is an Outer Membrane and a continuous Inner Membrane, of which the latter forms several invaginations called Cristae. Encased inside the inner membrane is the matrix. Because this organelle generates the source of chemical energy of the cell, it is also commonly referred to as the powerhouse of the cell.

Biochemically speaking, the overall reaction occurring in mitochondria can be summarized as:

C6H12O6 + 6O2              6CO2 + 6H2O