Mitochondria, abundance

Leon-Avila G, Tovar J (2004) Mitosomes of Entamoeba histolytica are abundant mitochondrion-related remnant organelles that lack a detectable organellar genome. Microbiol-SGM 150 1245-1250... 

Degree of Reduction of Electron Carriers in the Respiratory Chain The degree of reduction of each carrier in the respiratory chain is determined by conditions in the mitochondrion. For example, when NADH and 02 are abundant, the steady-state degree of reduction of the carriers decreases as electrons pass from the substrate to 02. When electron transfer is blocked, the carriers before the block become more reduced and those beyond the block become more oxidized (see Fig. 19-6). For each of the conditions below, predict the state of oxidation of ubiquinone and cytochromes b, clt c, and a + a3. 

Moore then explained how mitochondria are biological fuel cells. The oxygen reduction taking place in a mitochondrion is exactly the same as in a standard fuel cell. Using several enzymes and only earth-abundant elements, the mitochondrion converts electrochemical potential to biochemical work with efficiency greater than 90 percent. This is a steady-state process in which protons are pumped across the membrane to maintain its electrical potential. If... 

The ATP/ADP translocator, also called adenine nucleotide translocase, plays a vital role in the metabolism of aerobic cells because mitochondrial ATP is primarily consumed outside the mitochondria to support biosynthetic reactions. The translocator is the most abundant protein in the mitochondrion two molecules per unit of respiratory... 

FIG. 13.4 Longitudinal section of an L. mexicana amastigote. Note the abundant megasomes (Is) and the kinetoplast (kp) at the base of the short flagellum (f). Also shown and identified are the flagellar pocket (fp), the nucleolus (nl), chromatin (chr), and two sections through the single mitochondrion (m). (Reprinted with permission from ref 53.)... 

Mitochondrion-selective reagents for assessment of mitochondrial activity, localization and abundance, monitoring effects of pharmacological agents, such as anesthetics that alter mitochondrial function. Important role in apoptosis... 

Fig. 3. (A) A mitochondrion isolated from rabbit brain. Even after isolation and negative staining with isotonic ammonium molybdate, the mitochondrion has maintained a striking elongated appearance. The cristae are not very numerous, but many of them form complete septa. The matrix space is clearly recognizable, x 62,000. (B) A mitochondrion isolated from the masseter muscle of the rabbit, and treated as in Figure I. Also this mitochondrion has a non-spherical shape. The cristae are numerous, but the matrix space is more abundant than in rat heart. In this mitochondrion the tri-dimensional organization is particularly evident. X 120,000.

Electron transport and oxidative phosphorylation represent the most complex membrane processes yet uncovered in living mammalian cells. The broad outlines of this pathway are not much in question. Thus, the oxidation of one molecule of NADH by the respiratory chain results in the formation of three molecules of ATP. Three complexes along this chain—NADH-Q reductase, QH2-cytochrome c reductase, and cytochrome c oxidase—contain the sites where energy is transduced and enabled to interact with the ATPase to generate ATP (Fig. 2). Abundant evidence exists, as well, for the transfer of energy among these three complexes without the involvement of ATP synthesis for instance in ion translocation by the mitochondrion (Emster, 1977). 

The mitochondrion, as a primary source of ROS, is thus, itself, quite vulnerable to oxidative damage. Mn-SOD (sod2) is a mitochondrial form of the enzyme believed to play a key role in protecting the mitochondria from oxi tive injury. CuZnSOD (sodl). by far the more abundant form of SOD in... 

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