Cells, animal plant

Viruses are small infective agents consisting essentially of nucleic acid (either RNA or DNA enclosed in a protein coat). Some viruses contain additional lipoproteins, which may contain antigenic viral glycoproteins. Viruses are intracellular parasites with no metabolic machinery of their own. To replicate, they must attach to and enter the living host cell animal, plant, or bacteria and use its metabolic process. 

This theoretical prediction was beautifully confirmed in 1961 and 1962 by Francis Crick, Sidney Brenner, and their co-workers in Cambridge, in genetic studies with a virus. A virus is to all intents and purposes a packet of nucleic acid wrapped in a protein jacket. It exists by attacking cells - animal, plant, or bacterial -taking over the hosts protein and nucleic acid synthesizing systems and using them to make more viral protein and nucleic acid. With these it replicates its own structure several times, until it has used up and exhausted all the utilizable substrates present in the host cell. Finally, the virus bursts the host cell, releasing several new virus particles to hunt for fresh prey (see Plate 8). Viruses that... 

Biotransformations are carried out by either whole cells (microbial, plant, or animal) or by isolated enzymes. Both methods have advantages and disadvantages. In general, multistep transformations, such as hydroxylations of steroids, or the synthesis of amino acids, riboflavin, vitamins, and alkaloids that require the presence of several enzymes and cofactors are carried out by whole cells. Simple one- or two-step transformations, on the other hand, are usually carried out by isolated enzymes. Compared to fermentations, enzymatic reactions have a number of advantages including simple instmmentation reduced side reactions, easy control, and product isolation. 

Some mycehal fermentations exhibit early sporulation, breakup of mycehum, and low yields if the shear is excessive. A tip speed or 250 to 500 cm/s (8 to 16 ft/s) is considered permissible. Mixing time has been proposed as a scale-up consideration, but httle can be done to improve it in a large fermenter because gigantic motors would be required to get rapid mixing. Culturing cells from plants or animals is beset by mixing problems because these cell are easily damaged by shear. 

In most animal, plant, and microbial cells, the enzyme that phosphorylates glucose is hexokinase. Magnesium ion (Mg ) is required for this reaction, as for the other kinase enzymes in the glycolytic pathway. The true substrate for the hexokinase reaction is MgATP. The apparent K , for glucose of the animal... 

Protists Animals, plants, fungi (cell differentiation) Multi-cell... 

The eukaryotes these include animals, plants, fungi and protozoa, the DNA of which is enclosed in a membrane-enclosed organelle (the cell nucleus). They have a cytoskeleton (a fine membrane-like network in the interior of the cell, which provides stability) and contain mitochondria. Higher plants, as well as algae, are equipped with chloroplasts for photosynthesis. 

The importance of well-defined amounts of iron for the survival, replication and differentiation of the cells of animals, plants and almost all microorganisms (one... 

General extracellular fluid of animals Cerebrospinal fluid of animals Plant plasma Bloodstream containing special cells, erythrocytes Lymph containing special cells for protection Brain and spinal cord chemical communication in animals Movement of chemicals up and down stems and note phloem and xylem... 

There are no new messengers which act as cell-membrane transmitters in plants except cytokinins calcium is more widely used than in unicellular organisms but much less so than in animals. Plants respond to light via phosphorylation and changes from dormancy requires die change of cell calcium. Response times >1 s. There are several other sensors which are sometimes described as hormones, e.g. glucose and NO. 

Fats and oils, constituted by acylglycerolipids, represent a major subgroup of lipids. They are the most common class of medium-size molecules produced by living organisms. They are the main constituents of the storage fat cells in plants and animals. They have quite a similar chemical composition, as they are mainly composed of triglycerides, triesters of glycerol with fatty acids (FAs). 

Disruption of microbial cells (and, indeed, some animal/plant tissue types) is most often achieved by mechanical methods, such as homogenization or by vigorous agitation with abrasives. 

Figure 6.5 Diagrammatic representation of a cell homogenizer. This represents one of a number of instruments routinely used to rupture microbial cells, and in some cases animal/plant tissue...

Cell Respiration The metabolic process of all living cells (animal and plant) in which oxygen is used to provide a source of energy for the cell. [NIH]... 

Mn 0.76 0 9.7 430 44 471 358 4,569 Steel production, directly in pig iron manufacture and indirectly through upgrading ore to ferroalloys, dry cell batteries, plant fertilizers and animal feed, and brick colorant. 

Let s begin on a small scale the architecture of cells. The cells of plants and bacteria have strong cell walls that provide for maintenance of shape and protection against ontside forces. The cells of animals, including those of the human body, in contrast, lack cell walls. Animal cells make do with a fragile cell membrane. Our cells, consequently, have need of an internal architecture to meet the needs supplied by cell walls in other life forms. Cells have three types of internal architectural elements microtubules, intermediate filaments, and actin filaments. Each of these structures is composed of protein. 

Cholesterol is found almost exclusively in eukaryotic cells. Animal membranes contain substantially more cholesterol than plant membranes, in which cholesterol is usually replaced by other sterols. There is no cholesterol at all in prokaryotes (with a few exceptions). The inner mitochondrial membrane of eukaryotes is also low in cholesterol, while it is the only membrane that contains large amounts of cardiolipin. These facts both support the endosymbiotic theory of the development of mitochondria (see p. 210). 

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