Organisms, multicellular

Cell culture The in vitro growth of cells isolated from multicellular organisms. These cells are usually of one type. 

The abundance of many protein kinases in cells is an indication of the great importance of protein phosphorylation in cellular regulation. Exactly 113 protein kinase genes have been recognized in yeast, and it is estimated that the human genome encodes more than 1000 different protein kinases. Tyrosine kinases (protein kinases that phosphorylate Tyr residues) occur only in multicellular organisms (yeast has no tyrosine kinases). Tyrosine kinases are components of signaling pathways involved in cell-cell communication (see Chapter 34). 

Iinde75] Lindemayer, A., Developmental algorithms for multicellular organisms a survey of L-systems, Jour. ofTheo. Bio. 54 (1975) 3-22. 

Iinde89] Lindemayer, A. and P. Prusinkiewicz, Developmental models of multicellular organisms a computer grahics perspective, pp. 221-249 in [lang89]. 

This process occurs in the mitochondria, organelles present in the cells of all multicellular organisms (see Figs 6.8 and 6.26). Mitochondria have two membranes. The invaginations of the internal membrane into the inner space of the organelle (matrix space) are termed crests (from the Latin, cristae). 

In this section, two models of development were presented, a complex model consisting of a multioperon genome and a cytoplasm, and a simple model based on random Boolean networks. The simpler model was explained in more detail, as it is the basis for the extended example described here. This model utilizes both development and evolution to get to a cell that can develop into a multicellular organism able to seek a chemical trace. 

Deliberate degradation of biopolymers, even of cells, is very developed in multicellular organisms. We have already stressed the need for it externally in the constant remodelling of organisms during growth. There is also the obvious need for... 

Fungi are unicellular or multicellular organisms that are more highly evolved than bacteria (Chapter 17). They are members of the plant kingdom and include molds, mildew, smuts, rusts, and yeasts. They range in size from 3 to 50 fim. With the exception of yeasts, they are usually rod shaped and arranged end-to-end in strands or filaments. Yeasts are usually oval. 

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