Cells and chromosomes

Abstract

In all organisms, from bacteria to man, the fundamental unit of structure is the cell. A typical animal cell (Figure 1.1) is bounded by a semipermeable cell or plasma membrane which acts as a barrier between the exterior and the interior of the cell and controls the movement of substances in to and out of the cell. This membrane encloses the cytoplasm within which are suspended a variety of membrane-bound compartments called organelles; the cytoplasm also contains a matrix of filaments and tubules, the cytoskeleton which provides structural support for the cell.