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Mitochondria: How Our Bodies Produce Energy from Nutrients – Thomas DeLauer…
Mitochondria are known as the powerhouses of the cell and are found in the cells of every complex organism. Mitochondria are organelles that act like a digestive system which takes in nutrients, breaks them down, and creates energy rich molecules for the cell. They are 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 and they produce about 90% of the chemical energy that cells need to survive.
They are made of two membranes: The outer membrane covers the organelle and contains it like a skin – The inner membrane folds over many times and creates layered structures called crista. The fluid contained in the mitochondria is called the matrix. The folding of the inner membrane increases the surface area inside the organelle – since many of the chemical reactions happen on the inner membrane, the increased surface area creates more space for reactions to occur.
Cellular Respiration in Mitochondria:
The matrix is filled with water and proteins (enzymes) – Those proteins take organic molecules, such as pyruvate and acetyl CoA, and chemically digest them. Proteins embedded in the inner membrane and enzymes involved in the citric acid cycle ultimately release water and carbon dioxide molecules from the breakdown of oxygen and glucose. The mitochondria are the only places in the cell where oxygen is reduced and eventually broken down into water. Mitochondria are also involved in controlling the concentration of calcium (Ca2+) ions within the cell – they work closely with the endoplasmic reticulum to limit the amount of calcium in the cytosol.
Multiple Other Functions of the Mitochondria:
As Energy Converters- Mitochondria, using oxygen available within the cell convert chemical energy from food in the cell to energy in a form usable to the host cell. The process is called oxidative phosphorylation and it happens inside mitochondria. In the matrix of mitochondria the reactions known as the citric acid or Krebs cycle produce a chemical called NADH. NADH is then used by enzymes embedded in the mitochondrial inner membrane to generate adenosine triphosphate (ATP) – In ATP the energy is stored in the form of chemical bonds. These bonds can be opened and the energy redeemed. In return the host cell provides physical protection and a constant supply of food and oxygen.
As Determinators- Recent research indicates that in addition to converting energy mitochondria play quite a large part in determining when a cell will die by ordinary cell death (necrosis) or programmed cell death (apoptosis.) In apoptosis the mitochondrion releases a chemical, cytochrome c, and this can trigger programmed cell death. Mitochondria are also thought to influence, by exercising a veto, which eggs in a woman should be released during ovulation and which should be destroyed by programmed cell death (apoptosis.) This is part of a process called atresia – in this process mitochondria and the nucleus of the cell in which the mitochondria reside, are screened for biochemical compatibility. The pairs that are incompatible are shut down by programmed cell death.
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