Metabolism Energy

There are two possible life strategies for adapting to the environment, based on alternative modes of metabolism, active and sluggish. The two extremes are part of a continuous series which includes a number of intermediate forms. Examples will be given of fish which use the first, second and intermediate strategies of living. 

Differences in the motor activity of animals are reflected in the energy used, so it is useful to examine the intensities of oxygen consumption. 

Active fish have a better developed capillary system in the red muscle to supply oxygen to the mitochondria, and a higher haematocrit (Blaxter et al., 1971). The red muscle tissue also contains more cytochromes (respiratory proteins), and exhibits more cytochrome oxidase activity, which is responsible for transferring electrons in die respiratory chain, more efficient respiration control (oxidative phosphorylation and P/O coefficient) and a greater Atkinson charge, which characterizes energy reserve accumulated in adenyl nucleotides  

Emeretli (1990) demonstrated a convincing link between the activity of succinic dehydrogenase in the red muscle mitochondria of Black Sea species and their motor activity. This enzyme is one of the most important in the Krebs cycle, which controls the intensity of aerobic energy metabolism. 

In the muscle of active fish such as horse-mackerel and pickerel, the antiox-idative enzymes superoxide dismutase and catalase are more active than in the more sluggish scorpion fish (Rudneva-Titova, 1994 Rudneva-Titova and Zherko, 1994). 

Although values for A are not well understood, the Arrhenius equation can, on rearrangement, be used to calculate 

Two main sources of energy for metabolism are carbohydrates and fats (lipids). Proteins have less importance as an energy supplier. Knowledge of the total energy (AH) content of the major body fuels is necessary to understand how energy requirements are met by different fuels. 

The reactions for representative food fuels, glucose and palmitic acid, will be used to indicate differences in AH values. The subscripts s, , and g (solid, liquid, and gas, respectively) indicate the phase of the material under 1 atm, the pressure at which the reaction is carried out, and at the given temperature. The AH values given are standard heats of formation, since all reactants are in their standard (natural) state for the temperature given. 

Oxidation of 1 mol of glucose a carbohydrate) to carbon dioxide and water  

When production of ATP from ADP takes place directly during a reaction, as in this case, the process is known as substrate-level phosphorylation. 

Alternatively, ATP may be produced indirectly. Most biological oxidations involve the removal of hydrogen from a substrate. However, the final combination of hydrogen with oxygen to form water occurs only at the end of a series of reactions. A typical example is the removal of hydrogen coupled to nicotinamide adenine dinucleotide (NAD ), as illustrated in Fig. 9.2 for the oxidation of isocitrate to a-ketoglutarate. 

In this way the glucose is energised for subsequent biosynthetic reactions. In other reactions, such as the first stage of fatty acid synthesis, ATP provides the energy and is broken down to AMP and inorganic phosphate  

The role of ATP in trapping and utilising energy may be illustrated diagranunatically as shown in Fig. 9.3. 

Fixation of energy in the form of ATP is a transitory phenomenon and any energy produced in excess of immediate requirements is stored in a more permanent form 

There are many reports which show that humic acids (HA), prepared from 

Although much of the work has centred on the influence of HA on respiration, some reports indicate that fulvic acid (FA) can sometimes 

Ihus far only the effects on respiration in higher plants have been 

In evaluating an effect of hiamic substances on respiration, both uptake and CO output should be considered and the Respiratory Quotient CO iO calculated. Although the value of the Respiratory Quotient (R.Q.) 

Zea mays and Cuourhita maxima, but in no case was there a significant change 

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This type of correlation applies to almost any siibstrate involved in cellular energy metabolism and is supported by experimental data and energetic considerations. However, it is based on assumptions true at or near the steady-state equilibrium conditions and may not be valid... 

Mitochondria Mitochondria are organelles surrounded by two membranes that differ markedly in their protein and lipid composition. The inner membrane and its interior volume, the matrix, contain many important enzymes of energy metabolism. Mitochondria are about the size of bacteria, 1 fim. Cells contain hundreds of mitochondria, which collectively occupy about one-fifth of the cell volume. Mitochondria are the power plants of eukaryotic cells where carbohydrates, fats, and amino acids are oxidized to CO9 and H9O. The energy released is trapped as high-energy phosphate bonds in ATR... 

FIGURE 14.21 The structures of creatine and creatine phosphate, guanidiniutn compounds that are important in muscle energy metabolism. 

Define the differences in carbon and energy metabolism between photoautotrophszxidphotoheterotropHs, and between ehemoau-totropHs and ehemoheterotropHs. 

Atkinson, D. E., 1977. Cellular Energy Metabolism and Its Regulation. New York Academic Press. 

Dickerson, R. E., 1980. Cytochrome rand die evolution of energy metabolism. Scientific American 242(3) 137—153. 

Horton, E. S., and Terjung, R. L., eds. 1988. Exercise, Nutrition and Energy Metabolism. New York Macmillan. 

The main product appears as a result of primary energy metabolism. Examples production of biomass, ethanol and gluconic acid. 

The main product arises indirectly from energy metabolism. Examples dtric add and some amino adds. 

The main product is independently elaborated by the organism and does not arise directly from energy metabolism (die product is a secondary metabolite). Example antibiotics such as penicillin and streptomycin. 

The main product arises indirectly from energy metabolism. 

Sulfonamides Trimethoprim Dapsone Isoniazid Modification of energy metabolism... 

Brain structure below the thalamus and main portion of the ventral region of the diencephalon, controlling homeostatic and nonhomeostatic basic body and brain functions, including circadian and feeding rhythms, energy metabolism, thermogenesis, sympathoadrenal, and neuroendocrine outflow (secretion of hormones by the pituitary gland), behavioral state and memory functions. 

Lefebvre P, Chinetti G, Fruchart J-C et al (2006) Sorting out the roles of PPARa in energy metabolism and vascular homeostasis. J Clin Invest 116 571-580... 

TPP-dependent enzymes are involved in oxidative decarboxylation of a-keto acids, making them available for energy metabolism. Transketolase is involved in the formation of NADPH and pentose in the pentose phosphate pathway. This reaction is important for several other synthetic pathways. It is furthermore assumed that the above-mentioned enzymes are involved in the function of neurotransmitters and nerve conduction, though the exact mechanisms remain unclear. 

Atkinson, D.E. (1977). In Cellular Energy Metabolism and its Regulation. Academic Press, New York. Babcock, G.T. Wikstrom, M. (1992). Oxygen activation and the conservation of energy in cell respiration. Nature 356, 301-309. 

Figure 2. Force generation and energy metabolism in human quadriceps femoris muscle stimulated intermittently at 20 Hz, with 1.6 sec tetani with 1.6 sec rest periods between tetani. The upper panel shows force, ATP turnover rate, and pH the middle panel, the concentrations of PCr, P and lactate and the lower panel, ATP, ADP, IMP, H, and calculated H2PO4. From Hultman et al. (1990), with permission from Human Kinetics Publishers.

Hultman, E., Greenhaff, P.L., Ren, J.M., Soderlund, K. (1991). Energy metabolism and fatigue during intense muscle contraction. Biochem. Soc. Transact. 19, 347-353. 

Saltin, B. Costill, D.L. (1988). Fluid and electrolyte balance during prolonged exercise. In Exercise, Nutrition, and Energy Metabolism (Horton, E.S. Teijung, R.L., ed), pp. 150-158, MacMillan. New York. 

Succinic semialdehyde (SSA) is synthesized in the mitochondria through transamination of y-aminobutyric acid (GABA) by GABA transaminase (GABA-T). Most of the SSA is oxidized by SSA dehydrogenase (SSA-DH) to form succinate, which is used for energy metabolism and results in the end products CO2 + H2O, which are expired. A small portion of SSA (<2%) is converted by SSA reductase (SSA-R) in the cytosol to GHB. GHB may also be oxidized back to SSA by GHB dehydrogenase (GHB-DH). 

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