Prokaryotic cells differentiation

Zuber, H. (1983) in Photosynthetic Prokaryotes Cell Differentiation and Function (Papageor-giou, G.C. and Packer. L.. cds.) pp. 23-42, Elsevier, Amsterdam. 

Peschek GA, Schmetterer G, Lauritsch G, Muchl R, Kienzl PF and Nitschmann WH (1989) in Papageorgiou GC and Packer L, eds. Photosynthetic prokaryotes cell differentiation and function, pp. 147-162, Elsevier, New York, New York. 

Single internal cytoplasm Periplasm as second compartment As for prokaryote plus internal vesicles and organelles As for unicellular eukaryote plus cell/cell differentiation Organs and extracellular body space Animals with a nervous system senses and a brain able to search external space... 

The control of cellular proliferation and differentiation in response to external stimuli is achieved by signal transduction pathways, which are regulated in part by the co-ordinated action of protein kinases and phosphatases. In eukaryotic cells the protein kinases involved fall primarily into two classes, those that phosphorylate tyrosine residues and those that are specific for serine and threonine residues. Prokaryotic cells also rely on protein phosphorylation cascades for regulation of cellular activities, but the kinases involved are primarily histidine kinases, which are part of the sensing domain of two-component regulatory systems. These histidine kinases and their associated response regulators are involved in a range of adaptive responses by bacteria. 

Eukaryotic cells are found in protists, fungi, plants, and animals. Most eukaryotic cells are larger than prokaryotic cells. They contain many organelles, which are membrane bound areas for specific functions. Their cytoplasm contains a cytoskeleton which provides a protein framework for the cell. The cytoplasm also supports the organelles and contains the ions and molecules necessary for cell function. The cytoplasm is contained by the plasma membrane. The plasma membrane allows molecules to pass in and out of the cell. The membrane can bud inward to engulf outside material in a process called endocytosis. Exocytosis is a secretory mechanism, the reverse of endocytosis. The most significant differentiation between prokaryotes and eukaryotes is that eukaryotes have a nucleus. 

Distinct intermitotic phases are found in eukaryote cells but are not so obvious in prokaryote cells (Lark, 1963) and, especially in the light of the phenomena just discussed, may be considered a prerequisite for cell differentiation. Those organisms described above which do not possess a G1 phase in their division cycles (Bostocket al., 1966 Guttes et al., 1967 Ord, 1968) do not show an elaborate sequence of cell specialization. The presence of the G1 reflects a precise control over the timing of the initiation of nuclear DNA synthesis and suggests that some component of the initiation mechanism may be labile since initiation usually occurs only once in each division cycle. In differentiated tissues it appears the G1 phase provides a time in the division cycle where a cell can be held in a nondividing state in order to perform a specialized metabolic role. 

The approach recruited to chemical proteomics in Reference [17] is called SILAC (stable isotope labeling with amino acids in cell culture) and is important in comparative proteomics (Figure 1). SILAC works well with cultured mammalian cells, but prokaryotes defeat it by metabolizing the label (usually supplied in lysine and arginine) into other amino acids. For applications beyond cultured eukaryotic cells, the reductive methylation route to differential labeling [18] is among the alternatives [15]-... 

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