What are mitochondria and what do they do?
The “powerhouses of the cell”, that’s how many people know mitochondria. The parts of cells that turn sugars, fats and proteins that we eat, into forms of chemical energy that the body can use to carry on living.
Every living thing is made of cells: tiny compartments contained by a membrane. Cells are the smallest things that can reproduce themselves. When we look inside cells, we see that they have sub-compartments that are smaller still, known as “Organelles” which perform different functions that are essential for the cell to live.
Mitochondria are organelles found in the cells of every complex organism. They produce about 90% of the chemical energy that cells need to survive. No energy; no life! So it’s easy to see why when mitochondria go wrong, serious diseases are the result, and why it is important we understand how mitochondria work.
However, mitochondria do much more than just produce energy. They also produce chemicals that your body needs for other purposes, break down waste products so they’re less harmful, and recycle some of those waste products to save energy.
Mitochondria also have a special role in making cells die (apoptosis). This may sound strange, but it is vital for the processes of growth and development. Sometimes cells don’t die when they should and start to grow uncontrollably. This is how a tumour starts to grow, so you shouldn’t be surprised that mitochondria play an important part in cancer and are seen as targets for anti-cancer drugs.
To produce all of that energy, mitochondria require oxygen. Mitochondria effectively burn your food in a carefully controlled way to produce that chemical energy through a process called “oxidative phosphorylation”. And just as a fire goes out without oxygen, if mitochondria lack oxygen, they also stop working => No energy; No life!
During a heart attack or a stroke, the blood stops delivering oxygen to the heart and brain. These two organs do a lot of work and need a lot of energy. Without oxygen, the mitochondria stop working, and the cells in the brain or heart are damaged or even die. Perversely, if the oxygen does return, then the mitochondria get overwhelmed and produce a lot of “free radicals”. These are very reactive chemicals which cause a lot of additional damage – called “Reperfusion injury”.