Mitochondria changes

The control of the respiration process and ATP synthesis shifts as the metabolic state of the mitochondria changes. In an isolated mitochondrion, control over the respiration process in state 4 is mainly due to the proton leak through the mitochondrial inner membrane. This type of control decreases from state 4 to state 3, while the control by the adenine nucleotide and the dicarboxylate carriers, cytochrome oxidase, increases. ATP utilizing reactions and transport activities also increase. Therefore, in state 3, most of the control is due to respiratory chain and substrate transport. 

The redox potential is a measure of oxidative phosphorylation maintained by the hepatic mitochondria. Changes of the redox potential are reflected by alterations to the ratio of acetoacetate to 3-hydroxybutyrate (also called the ketone body ratio). This ratio is dependent on mitochondrial 3-hydroxybutyrate dehydrogenase activity, which catalyzes the interconversion of acetoacetate and 3-hydroxybuyrate (Laun et al. 2001 Fukao, Lopaschuk, and Mitchell 2004 Hidaka 2004 Matsumoto et al. 

Perhaps of most Importance Is yeast s unusual ability among eukaryotes to be able to live anaerobically and to derive Its ATP by nonresplratory glycolysis. Under these conditions, as seen under the electron microscope, the mitochondria change morphologically to what are called promltochondrla (14), and the cells become auxotrophic for sterol (11) and unsaturated fatty acid such as oleate (15). Aerobically yeast derives Its sterol and unsaturates by biosynthesis, and for both types of compound there are biosynthetic steps Involving mixed function oxidases,, for the formation of squalene oxide... 

A third study focused on the effect of CLA and vitamin A on the polyunsaturated fatty acid (PUFA) composition, chemiluminescence and peroxidizability index of microsomes and mitochondria isolated from rat liver (43). The PUFA composition of microsomes and mitochondria changed by CLA and vitamin A treatment. The simultaneous analysis of peroxidizability index, chemiluminescence and fatty acid composition demonstrated that CLA is more effective than vitamin A in protecting microsomes or mitochondria against peroxidative damage. 

The cell organellae in woody plants are the nucleus, mitochondrion, rough-endoplasmic reticulum (r-ER), smooth endoplasmic reticulum (s-ER), Golgi-body, plastid, vacuole, microbody, etc. Their functions are very complicated, and some have definite roles in the biosynthesis of cell-wall components. Hence, changes in size of cell organellae are likely to occur, since cell-wall composition depends upon the stage of wall development. 

The mitochondrial membrane potential Em (or Ay) is the potential difference measured across a membrane relative to a reference electrode present in the surrounding solution.176 For both mitochondria and bacteria Em normally has a negative value. The Gibbs energy change AyH+ for transfer of one mole of H+ from the inside of the mitochondrion to the outside, against... 

Let s now consider how much free energy is released by moving protons into the mitochondrion. Is it really enough to drive the synthesis of ATP The free energy change depends both on the ratio of the proton concentrations on the two sides of the membrane and on the difference between the electric potentials on the two sides. 

Fig. 23.1. ADP-driven volume and structural changes of mitochondria. Depending on the ADP concentration, the morphology of the interior changes as well as the volume of the mitochondrion, effectively regulating ATP production. Reproduced with permission [6]...

Huang, J., S. Friedhehn, D.F. Matzinger, and C.S. Levings III Flower-enhanced expression of a nuclear-encoded mitochondrial respiratory protein is associated with changes in mitochondrion number The Plant Cell 6(1994)439-448. 

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