Biological Importance of Cellular Respiration

When you see the word "respiration," you think of breathing. This function is not something most people associate with cells, those microscopic bits that make up every living thing. Just as animals, including humans, need to absorb oxygen in order to live, individual cells need to produce the energy needed to function properly.

Definition

• Energy has to come from somewhere. Cells get theirs by breaking down sugars and other compounds, releasing the energy needed to do their work. This process, called cellular respiration, takes place in parts of the cell called mitochondria.

The Process

• Animals breathe in oxygen. Some of these molecules make their way into the mitochondria, and in conjunction with the sugars ingested through food, are used by the cell to produce, among other things, carbon dioxide and water. The whole point of cellular respiration is to take the chemical energy from food and store it in the chemical bonds of ATP (adenosine triphosphate). The carbon dioxide produced makes its way to the lungs, where the animal expels it when exhaling.

Types of Cellular Respiration

• Aerobic cellular respiration requires the use of oxygen, and is how a cell makes ATP. The role oxygen plays is important because the oxygen, when combined with hydrogen ions, makes water, which prevents electrons from building up in the electron transport system that moves the electrons around between cell membranes.
  Anaerobic respiration does not need oxygen. One form of this type of respiration is fermentation, a process that donates electrons and hydrogen ions to other molecules. One place this is helpful is in certain types of muscle cells that run low on oxygen when used (such as "fast twitch muscles" that are used when running). Fermentation allows these cells to produce needed ATP without the use of oxygen.

When Things Go Wrong

• Sometimes the mitochondria fail, and when that happens, cells are deprived of the energy they need to survive. They begin to die, and the result can be the failure of entire body systems.
  Some of the known mitochondrial deficiencies include Alper's Disease, a rare genetic disorder that causes deterioration of the gray matter in the brain; Barth Syndrome, a genetic disorder passed from mothers to sons, that can cause weak heart muscles, growth delays, and a reduction in a type of white blood cell that fights infection; and Luft Disease, a very rare condition that causes the metabolism to run in overdrive. People with this disease can eat voraciously yet remain thin, or sweat even in cold weather because the excess energy the mitochondria produce is converted into heat.

Keeping the Mitochondria Healthy

• One way to help ensure healthy mitochondrial function is supplementing the diet with antioxidants and eating fewer calories. Scientists theorize that by reducing the amount of oxygen used by mitochondria, they produce fewer damaging oxidants. This can help cells live longer.