Читать книгу Algorithms in Bioinformatics - Paul A. Gagniuc - Страница 30

Compartmentalization is not a condition for life; however, a closed environment for biochemical containment might be. Most likely, unicellular species that evolved in water had fewer survival issues related to mechanics and gravity. To obtain a specialization, some of these species evolved a cooperation between internal biochemical processes rather than between individual cells. Thus, their volume and shape increased to the point where a single cell began to resemble a multicellular organism. Such unicellular organisms contain multiple nuclei, and for historical reasons are called coenocytes (Greek – coeno, “common”; cyte, “box”). Nevertheless, the virtual “cells” of these unicellular organisms are not defined by a physical barrier. This virtualization may be achieved only through controlled biochemical interactions between concentration gradients of different types of molecules (i.e. from gradients of simple nucleic acids, amino acids, fatty acids and sugars, up to RNA and proteins). Spatially spaced point sources of such chemical and biochemical gradients can form a well-organized virtual structure in these unicellular organisms. Moreover, the biochemical versatility can continue up to the point of inclusion of smaller unicellular species to form a biochemical symbiosis.