|
Have you ever wondered how your cells get their energy? It is actually through a process of ATP breakdown and formation that takes place in the innermost recesses of the mitochondria. Read this article to find out about mitochondria, the powerhouses of the cell.
Mitochondria are interesting to look at under a microscope. This is because, unlike some cell organelles, they contain two membranes. The outer membrane contains channels to let thing in and out of the mitochondria. The inner membrane folds around to create the body of this organelle. They can be round, but are usually long and oval to look at. This inner fold, or cristae, of the mitochondria contains proteins, ribosomes and DNA-related materials inside it. The cristae are very important. The hold and organize the electron transport chain and also create a space where the gradient of hydrogen ions can be raised, fueling the energy-making cycle. It is actually possible to separate this inner cristae from the other membrane, creating a new entity. These mitochondrion hybrids are known as "mitoplasts."
The purpose of mitochondria is to get energy from high-energy phosphate bonds, or ATP (adenosine triphosphate). These bonds are created by the body when food is broken down. When energy has been taken from ATP, it becomes ADP (adenosine diphosphate), and vice-versa. Various energy-processing areas of the cell create and break down ATP.
Mitochondria use the Krebs cycle to take electrons from food particles. The electrons are the fuel for the ATP-producing process. The Krebs cycle works like this: Pyruvate, or a molecule of three carbons, enters the mitochondria and is broken down into a 2 carbon molecule, AcetylCoA. This joins to another molecule and enters the Krebs cycle. Together, they form citric acid. As this 6-carbon molecule is broken down, hydrogen and carbon molecules are released. The carbon molecules enter the cycle to be used again. The hydrogen molecules are the gain from this whole process. As the cycle runs around again, hydrogen ions are added to some of the steps in the Krebs cycle. A gradient is created between the inside of the cristae and the outside, because the higher concentration of hydrogen ions is inside.
Therefore, hydrogen electrons are donated from the Krebs cycle. They are carried to electron transport pumps. When the carriers, NAD and FAD, common cell carriers, release them, they are "oxidized." An imbalance of ions inside the cristae to the outside generates energy to create ATP. The hydrogen ions run the pumps to "phosphorylate" ADP, or make them ATP.
The point of the entire cycle is to create more and more hydrogen ions, which fuel the pumps. This process never stops, because fuel is constantly needed in the cell.
Scientists view these organelles today by staining them, then viewing them through a microscope. Mitochondria are incredibly important to our understanding of the human body. In fact, if there is a defect in mitochondrial function and formation, life cannot be sustained. Mitochondria, because of their function, are essential to human existence.
|
| |
