thickness. As an organelle it is very changeable. Its form and structure is
insufficiently clarified. If there are ribosomes on its surface, it is called rough
or granular, and when there are not — smooth (Fig. 2–63). The area of ER in
the cells is large and sometimes can rich about 16% of their volume.
In ER-membranes there are two types of redox systems: NADPH-reductase and
cytochrome P-450. By means of these systems there are realized a detoxication of
compounds harmful to the cell and transformation of saturated aliphatic acids into
unsaturated. In the smooth ER there are formed carbohydrates, lipids and terpenoids,
and in the granular one there are synthesized membrane proteins and enzymes necessary
for the synthesis of cell-wall polysaccharides and many other secretory proteins. Through
endoplasmic reticulum the transporat of many substances in the cell is realized. It also
participates in intercellular relations, accomplishing the connection between different cells.
image
Figure 2–63. Electron micrograph of a section of mammal cell, where smooth and rough endoplasmic reticulums are seen (Courtesy of G. Palade; From Alberts et al., 1986).
Golgi Apparatus (Complex)
It is a cell organelle called after its discoverer Camilo Golgi (1898 a, b, 1899). It represents
a netlike structure built of dictyosomes (Greek: dyctyes — net), bubbles and
intercistern formations. Each dictyosome (Fig. 2–64 A, B) is built of several interconnected
cisterns. The cisterns are limited by membranes, 7—8 nm in thickness. On the one pole, called
regenerative, there proceeds a new forming of dyctyosomes from the membranes of the
smooth endoplasmic reticulum. On the other pole, called secretory, bubbles are formed
which contain substances intended to be secreted.
In dictyosomes glycoproteins andglycolipids are formed and there proceed
accumulation and “maturation” of components necessary for building the cell membranes.
The content of bubbles, whose membranes are built in plasmalemma, is transported up to the cell