Text № 4 «proteins and protoplasm»

Proteins represent the stream¹ of life. They make up the vital part of that essential jelly material of the living cell – the protoplasm. The beginning of life on this and perhaps a few other planets must have been associated with the formation of proteins. This word means “to take first place”, for there is no life without proteins. If you would like to see proteins, look over your own body, or you can look at one that is practically pure, that is the white of an egg, which is almost all protein or albumen and water. Usually these lost essential of life’s materials have the indefinite and glue-like form known as a colloid though some of them have been separated as pure and definite crystals. Though the detailed² structures of the molecules are complex, there are only a few chemical elements which enter into their composition. Most proteins contain 51 to 55 per cent carbon, about 7 per cent hydrogen, 20 to 23 per cent oxygen, 15.5 to 18.7 nitrogen, 0.3 to 2.0 per cent sulphur. Some of them also contain a little phosphorus or iron. Nature makes some tremendous structures out of these few materials.

1 – течение, основа

2 – мельчайший

Text № 5 «vitamins»

Vitamins are organic compounds essential for the normal functioning of the body, and usually obtained from foods. Vitamins are present in minute quantities compared to the other utilizable components of the diet - proteins, fats, carbohydrates, and minerals.

Almost all knowledge of the vitamins has been obtained during the 20^th century. The discovery of the vitamins has primarily been the result of two lines of investigation: the study of nutritional disease in people and the feeding of purified diets of known composition to experimental animals. In this way vitamin deficiency diseases, known as avitaminoses, have been described.

Synthetic and natural vitamins usually have the same biological value. The use of vitamins has been the subject of different research. The principal members of the vitamin groups are A, B, C, D, E, K. The functions of the vitamins are extremely varied and important for health, development and growth.

Text № 6 «minerals and human body»

There are 88 chemical elements in the crust of the earth. All the plant and animal life is composed of some of these elements.

Many chemists have contributed to our knowledge of the roles of the various mineral elements in nutrition.

Calciumis the most abundant mineral in the body. The average man contains over 2.5 lb* of it of which 93% is in the bones and teeth. There is only 1 part of calcium in 10,000 parts of blood, but it serves several purposes; it controls the texture of the cell membranes, affects the heartbeat and the nerve and muscle action, and regulates the activity of several enzymes.

The bones and teeth contain about half as much phosphorus as calcium, but the soft tissues contain more phosphorus than calcium.

Phosphorus, like calcium, is not simply a structural element of the body but it takes part in metabolism. Phosphorus combines with the fats and the proteins to form compounds that are essential components of the heart, brain, and other vital organs.

There is less than 3 gm of iron in the adult human body. It is a part of several tissues, although most of it is in the blood and nearly all of it is combined with protein. The iron in blood is part of the protein, hemoglobin, which makes up the greater portion of the red corpuscles. It is the iron in this protein that carries oxygen to all the tissues of the body; each molecule of hemoglobin can carry four molecules of oxygen. If there is not enough iron supplied in the blood, anemia results.

* libra = pound – фунт (423г)