Protoplasm components

Cholesterol is an ubiquitous protoplasmic component in living organisms, a precursor of steroidal hormones and bile acids, and is synthesized in most tissues. Cholesterol undergoes constant turnover through degradation processes counterbalanced by exogenous supply and endogenous formation. 

As early as 1848, it had been suggested that sensory receptors transduce only one sensation, independent of the manner of stimulation. Behavioral experiments tend to support this theory. In 1919, Renqvist proposed that the initial reaction of taste stimulation takes place on the surface of the taste-cell membrane. The taste surfaces were regarded as colloidal dispersions in which the protoplasmic, sensory particles and their components were suspended in the liquor or solution to be tested. The taste sensation would then be due to adsorption of the substances in the solution, and equal degrees of sensation would correspond to adsorption of equal amounts. Therefore, the rate of adsorption of taste stimulants would be proportional to the total substances adsorbed. The phenomenon of taste differences between isomers was partly explained by the assumption that the mechanism of taste involves a three-dimensional arrangement for example, a layer of fatty acid floating on water would have its carboxylic groups anchored in the water whereas the long, hydrocarbon ends would project upwards. 

Somatic motor and sensory neurons that give rise to PNS axons maintain large fractions of their total protoplasmic bulk within the CNS. Many of the extracellular matrix components and axonal guidance molecules involved in... 

Cellulose, the most abundant polysaccharide, is the structural component of plant tissues starch is the energy compound stored predominantly in seeds and tubers glycogen is the animal counterpart of starch, but with shorter, more numerous branches. Cellulose and starch cohabit plant tissues with hemicellulose, protoplasm, lipid, and mineral matter in an organization interrupted by intercellular spaces that can amount to more than 50% of the total volume of some fruits and vegetables. A number of useful polysaccharides and their origins are listed in Table I. 

In contrast to LHCI, the light-harvesting chlorophyll a/b-antennae complex of photosystem II (LHCII) is the major component of the particles on the complementary protoplasmic fracture face of appressed membranes (PFs) (Simpson, 1979, Olive et al., 1979), and does not appear to be a significant component of the reaction centre EFs particles, although this is disputed. The LHCII in PFs particles is, nevertheless, in contact with the reaction centre particles and may provide a pathway for excitation energy transfer between several photosystem II reaction centres. 

All microorganisms require varying amounts of a large number of nutrients. These are required because they are necessary components of bacterial protoplasm. The nutrients can be divided into three groups macro, minor, and micro. The macronutrients are those that comprise most of the biomass. These are given by the commonly accepted formula for biomass (Cml 2I ). The carbon, hydro-... 

Cytoplasm - The cytoplasm, or protoplasm, of bacterial cells is where the functions for cell growth, metabolism, and replication are carried out. It is a gellike matrix composed of water, enzymes, nutrients, wastes, and gases and contains cell structures such as ribosomes, a chromosome, and plasmids. The cell envelope encases the cytoplasm and all its components. Unlike the eukaryotic (true) cells, bacteria do not have a membrane enclosed nucleus. The chromosome, a single, continuous strand of DNA, is localized, but not contained, in a region of the cell called the nucleoid. All the other cellular components are scattered throughout the cytoplasm. 

Fig. 112.—Volvox globaior. Mature colony in center (i) sexual cells (20) endochrome of primary cell has resolved itself into a cluster of secondary cells (la, o and 5) antherozoids (6, 7) bundle separated into component antherozoids in cavity of primary cell (la ) breaking of wall of primary cell showing escape of antherozoids into cavity of volvox sphere (la ) egg cells (i, d) flask shaped germ (egg) cells with large vacuoles in protoplasm (ib, ) globular egg cell prepared to pass into cavity of volvox sphere (6 ) antherozoids collected about egg cell (3) oospore (4). (Carpenter.)...

Proteins are essential to all living matter and perform numerous functions as cellular components. Fundamental cellular events are catalyMsd by proteins called cn/ymes, while other proteins serve as architectural constituents of protoplasm and cell membranes. Most important arc the classes of hormones that are charactcriitcd us proteins or protein-like compounds because of their polypeplidic. structure. 

Cytoplasm. The extra nuclear components of the living cell, containing mitochondria, plastids, sphe-rosomes, etc. This, together with the nucleus, constitutes the protoplasm. The chemical constituents are chiefly proteins, plus a high percentage of water. 

Moisture is also required for microbial activity as the primary component in bacteria protoplasm is water. If the bacteria do not receive enough water, they will die. However, oversaturation conditions can be detrimental. Too much water can inhibit gas exchanges, thereby depleting the airborne oxygen and rendering an anaerobic zone. Moisture levels are typically maintained by using water as the delivery medium for nutrient amendments and removal of degradation by-products. 

Protein Precipitation. The living part of a cell is the protoplasm, which consists of proteins, lipids, nucleic acids, a source of energy (usually carbohydrates), metabolic intermediates, certain inorganic ions, and cofactors necessary for the enzyme activity of many proteins. Because the proteins comprise the largest component of protoplasm (Table I), it is logical to look first at them as the seat of cell injury. It is perhaps for... 

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