Metabolism in animal cells

Major pathways for central metabolism in animal cells (based on Shuler and Kargi, 2002). 

THE VINCA ALKALOIDS FROM BIOSYNTHESIS AND ACCUMULATION IN PLANT CELLS, TO UPTAKE, ACTIVITY AND METABOLISM IN ANIMAL CELLS... 

Sottomayor M, Ros Bareelo A (2006) The Vinca alkaloids from biosynthesis and accumulation in plant cells, to uptake, activity and metabolism in animal cells. Stud Nat Prod Chem... 

This reaction sequence, which is the reverse of the propionate metabolism in animal cells, is ultimately equivalent to the reduction of pyruvate to propionate by NADH formed in glycolysis or in triose oxidation to acetate and CO2. 

Phosphatidylinositol, containing the optically inactive form of inositol - myoinositol, is a common constituent of animal, plant and microbial lipids. Often in animal tissues. It Is accompanied by small amounts of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-blsphosphate (polyphosphoinositides). These compounds have a rapid rate of metabolism in animal cells, and with their diacylglycerol metabolites have a major role in regulating vital processes. The topic has been reviewed [388],... 

Marine toxins modify the functions of many different types of ion channels in animal cell membranes. These channels may be important for maintaining the cell s resting potential, for generating electrical membrane signals, such as impulses, and for controlling hormonally triggered or metabolic responses. Thus toxins may depolarize membranes, leading to a (sometimes transient) increase in cellular activities, or they may... 

A successful tool in the early studies of metabolic pathways was blocking the pathway at some specific point. This could be done by the use of either mutants or inhibitors. Schekman et al have isolated a number of yeast mutants with blocks in their secretion pathway (Schekman, 1982). It is not yet known which proteins these mutations affect, but this is clearly a most promising approach for identifying those components involved in transport. In animal cells there are no cellular mutants with blocks in the intracellular transport of protein from the ER to the cell surface. There are, however, genetic diseases which affect the routing of lysosomal enzymes to the lysosomes (Neufeld et al, 1975 Sly and Fischer, 1982). For viruses it has been possible to isolate temperature-sensitive mutants in which a mutation in the viral glycoprotein arrests... 

Ethylene dibromide induced gene mutations, sister chromatid exchanges, chromosomal aberrations and cell transformation in animal cells. It induced mutations in two human lymphoblastoid cell lines, AHH-1 and TK6 in the absence of exogenous metabolic activation. Administration of radiolabelled ethylene dibromide to Wistar rats and BALB/c mice resulted in binding to DNA, RNA and proteins. [The nature of the binding was not characterized.]... 

The High Rate of Bacterial Metabolism Bacterial cells have a much higher rate of metabolism than animal cells. Under ideal conditions some bacteria double in size and divide every 20 min, whereas most animal cells under rapid growth conditions require 24 hours. The high rate of bacterial metabolism requires a high ratio of surface area to cell volume. 

Carbohydrate metabolism in a typical plant cell is more complex in several ways than that in a typical animal cell. The plant cell carries out the same processes that generate energy in animal cells (glycolysis, citric acid cycle, and oxidative phosphorylation) it can generate hexoses from three- or four-carbon compounds by glu-coneogenesis it can oxidize hexose phosphates to pentose phosphates with the generation of NADPH (the ox-... 

From the complementary duplex structure of DNA described in chapter 25, it is a short intuitive hop to a model for replication that satisfies the requirement for one round of DNA duplication for every cell division. In chapter 26, DNA Replication, Repair, and Recombination, key experiments demonstrating the semiconservative mode of replication in vivo are presented. This is followed by a detailed examination of the enzymology of replication, first for how it occurs in bacteria and then for how it occurs in animal cells. Also included in this chapter are select aspects of the metabolism of DNA repair and recombination. The novel process of DNA synthesis using RNA-directed DNA polymerases is also considered. First discovered as part of the mechanisms for the replication of nucleic acids in certain RNA viruses, this mode of DNA synthesis is now recognized as occurring in the cell for certain movable genetic segments and as the means whereby the ends of linear chromosomes in eukaryotes are synthesized. 

Biochemistry resulted from the early elucidation of the pathway of enzymatic conversion of glucose to ethanol by yeasts and its relation to carbohydrate metabolism in animals. The word enzyme means "in yeast," and the earlier word ferment has an obvious connection. Partly because of the importance of wine and related products and partly because yeasts are relatively easily studied, yeasts and fermentation were important in early scientific development and still figure widely in studies of biochemical mechanisms, genetic control, cell characteristics, etc. Fermentation yeast was the first eukaryote to have its genome elucidated. 

Lipids have several important functions in animal cells, which include serving as structural components of membranes and as a stored source of metabolic fuel (Griner et al., 1993). Eukaryotic cell membranes are composed of a complex array of proteins, phospholipids, sphingolipids, and cholesterol. The relative proportions and fatty acid composition of these components dictate the physical properties of membranes, such as fluidity, surface potential, microdomain structure, and permeability. This in turn regulates the localization and activity of membrane-associated proteins. Assembly of membranes necessitates the coordinate synthesis and catabolism of phospholipids, sterols, and sphingolipids to create the unique properties of a given cellular membrane. This must be an extremely complex process that requires coordination of multiple biosynthetic and degradative enzymes and lipid transport activities. 

McKeehan WL (1986), Glutaminolysis in animal cells, In Morgan MM (Ed.), Carbohydrate Metabolism in Cultured Cells, Plenum, New York, pp. 111-150. 

One of the pioneers of structured models in animal cell culture used a single-cell model (Batt and Kompala, 1989). Based on hybridoma metabolism (.Figure 8.6), the model was based on the formulation of four compartments amino acids (including the TCA precursors), the nucleotides (including DNA and RNA), the proteins, and lipids. The excreted byproducts (lactate and ammonia) and the excreted product (mAb) were also considered. However, although flexible for simulation of different... 

---