Farmasevtika instituti farmakologiya va klinik farmatsiya kafedrasi

Proteins Are Formed by the Granular Endoplasmic Reticulum. 
The granular portion of 
the endoplasmic reticulum is characterized by large numbers of ribosomes attached to the outer 
surfaces of the endoplasmic reticulum membrane. As discussed in Chapter 3, protein molecules are 
synthesized within the structures of the ribosomes. The ribosomes extrude some of the synthesized 
protein molecules directly into the cytosol, but they also extrude many more through the wall of the 
endoplasmic reticulum to the interior of the endoplasmic vesicles and tubules, into the 
endoplasmic 
matrix.
Synthetic Functions of the Golgi Apparatus. 
Although the major function of the Golgi 
apparatus is to provide additional processing of substances already formed in theendoplasmic 
reticulum, it also has the capability of synthesizing certain carbohydrates that cannot be formed in the 
endoplasmic reticulum. This is especially true for the formation of large saccharide polymers bound 
with small amounts of protein; important examples include 
hyaluronic acid 
and 
chondroitin sulfate. 
A 
few of the many functions of hyaluronic acid and chondroitin sulfate in the body are as follows: (1) 
they are the major components of proteoglycans secreted in mucus and other glandular secretions; (2) 
they are the major components of the 
ground substance 
outside the cells in the interstitial spaces, 
acting as fillers between collagen fibers and cells; (3) they are principal components of the organic 
matrix in both cartilage and bone; and (4) they are important in many cell activities including 
migration and proliferation. 
Extraction of Energy from Nutrients
—Functionof the Mitochondria 
The principal 
substances from which cells extract energy are foodstuffs that react chemically with oxygen—
carbohydrates, fats, and proteins. In the human body, essentially allcarbohydrates are converted into 
glucose 
by the digestive tract and liver before they reach the other cells of the body. Similarly, proteins 
are converted into 
amino acids 
and fats into 
fatty acids. 
Figure 2-14 shows oxygen and the 
foodstuffs— glucose, fatty acids, and amino acids—all enteringthe cell. Inside the cell, the foodstuffs 
react chemically with oxygen, under the influence of enzymes that control the reactions and channel 
the energy released in the proper direction. The details of all these digestive and metabolic functions 
are given in Chapters 62 through 72. To reconstitute the cellular ATP as it is used up, energy derived 
from the cellular nutrients causes ADP and phosphoric acid to recombine to form new ATP, and the 
entire process repeats over and over again. For these reasons, ATP has been called the 
energy currency 
of the cell because it can be spent and remade continually, having a turnover time of only a few 
minutes.