mitochondrial fusion and fission in cell life and death

When we are cold, we shiver to keep warm. Other roles for calcium in the cell include regulating cellular metabolism, steroid synthesis, and hormone signaling. Mitochondria play a part in this by quickly absorbing calcium ions and holding them until they are needed. Calcium is also necessary for muscle function, fertilization, and blood clotting, among other things.īecause calcium is so critical, the cell regulates it tightly. For instance, releasing calcium back into a cell can initiate the release of a neurotransmitter from a nerve cell or hormones from endocrine cells. Storing calciumĬalcium is vital for a number of cellular processes. Mitochondria release cytochrome C, which activates caspase, one of the chief enzymes involved in destroying cells during apoptosis.īecause certain diseases, such as cancer, involve a breakdown in normal apoptosis, mitochondria are thought to play a role in the disease. Mitochondria help decide which cells are destroyed. As cells become old or broken, they are cleared away and destroyed. Cell deathĬell death, also called apoptosis, is an essential part of life. When these chemical bonds are broken, the energy can be used. In molecules of ATP, energy is stored in the form of chemical bonds. NADH is used by enzymes embedded in the cristae to produce ATP. The Krebs cycle produces a chemical called NADH. This process is called oxidative phosphorylation. Mitochondria convert chemical energy from the food we eat into an energy form that the cell can use. Most ATP is produced in mitochondria through a series of reactions, known as the citric acid cycle or the Krebs cycle.Įnergy production mostly takes place on the folds or cristae of the inner membrane. The vast majority are involved in other jobs that are specific to the cell type where they are found.īelow, we cover a few of the roles of the mitochondria: Producing energyĪTP, a complex organic chemical found in all forms of life, is often referred to as the molecular unit of currency because it powers metabolic processes. In fact, only about 3 percent of the genes needed to make a mitochondrion go into its energy production equipment. Share on Pinterest Mitochondria are important in a number of processes.Īlthough the best-known role of mitochondria is energy production, they carry out other important tasks as well. So, in reality, these organelles are linked together in ever-changing networks.Īlso, in sperm cells, the mitochondria are spiraled in the midpiece and provide energy for tail motion. Around 40 percent of the cytoplasm in heart muscle cells is taken up by mitochondria.Īlthough mitochondria are often drawn as oval-shaped organelles, they are constantly dividing (fission) and bonding together (fusion). Cells with a high demand for energy tend to have greater numbers of mitochondria. For instance, mature red blood cells have none at all, whereas liver cells can have more than 2,000. Mitochondrial DNA is housed here (see below).ĭifferent cell types have different numbers of mitochondria. Containing hundreds of enzymes, it is important in the production of ATP. Matrix: This is the space within the inner membrane. They increase the surface area of the membrane, therefore increasing the space available for chemical reactions.

The inner membrane is where most ATP is created.Ĭristae: These are the folds of the inner membrane. Molecules can only cross the inner membrane in special membrane transporters. Because there are no porins in the inner membrane, it is impermeable to most molecules. Inner membrane: This membrane holds proteins that have several roles. Intermembrane space: This is the area between the inner and outer membranes. The outer membrane also hosts a number of enzymes with a wide variety of functions. This outer portion includes proteins called porins, which form channels that allow proteins to cross. Outer membrane: Small molecules can pass freely through the outer membrane. Mitochondria are split into different compartments or regions, each of which carries out distinct roles. Unlike other organelles (miniature organs within the cell), they have two membranes, an outer one and an inner one.

Mitochondria are small, often between 0.75 and 3 micrometers and are not visible under the microscope unless they are stained. Share on Pinterest A basic diagram of a mitochondrion

Mitochondrial fusion and fission in cell life and death