Методические указания по английскому языку по дисциплине английский язык предназначены для студентов изоп нгау всех направлений подготовки.
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SHARKSThere are about 300 species of sharks, from the 60cm Pygmy shark to the enormous White shark. They are found in all the seas of the world, but are most common in warm waters. Tiger shark. Weighing about 1,000 kilos and about 5 metres long, this is an extremely aggressive shark. It has a square narrow head, rounded teeth, and a striped body. It lives in tropical seas and likes shallow water. It is therefore very dangerous for swimmers. Whale shark. The largest shark - and the largest of all fish - the whale shark grows up to 15 metres long and weights up to 20 tonnes. It is grey with light yellowish marks on its body. Despite large size it is harmless to people, and feeds on small organisms. White shark. This is the most powerful and most aggressive of all sharks. It can grow up to 6 meters and weigh 3 tonnes. It has big, triangular teeth, a dark grey back and a dirty white underside. It prefers the open sea, living in tropical or temperate waters, but may come inshore at times. Hammerhead shark. Easily recognizable by its flattened, T-shaped head, the hammerhead grows to 5 metres in length and can weigh up to 400 kilos. It prefers tropical waters, has an aggressive character and can be dangerous. PROTEINS AND MINERALSNutritionally, proteins are important for growth, reproduction, lactation and optimum health. Protein is the main component of the soft tissues of the body; it is the structural constituent of the cells making up these parts and is vitally important in many biochemical substances, such as hormones, enzymes, immune bodies and blood. Proteins are also of considerable importance in the resistance to the recovery from various diseases. In a deficiency, for example, the capacity to fabricate antibody protein is low; the production of leukocytes and lymphocytes is decreased, and the bone marrow and lymphoid tissues depleted. Hormones are proteins that regulate body organs and their functions, enzymes digest food for further use in the body, immune bodies are their principal bacterial and viral defenders of the body; hemoglobin carries the oxygen to the cells so that they have energy; leukocytes and lymphocytes kill and digest bacteria and other foreign substances in the blood. Minerals are inorganic elements. Organic compounds, which contain carbon (such as carbohydrates, fat, protein and vitamins), will burn. Minerals become a part of skeletal structure, but also play essential role in digestion and in metabolism inside body cells. Calcium, phosphorus, magnesium, fluorine, and certain other mineral elements are integral part of the bone structure and of teeth. Approximately 99 percent of the calcium and 80 percent of the phosphorus present in the animal body are contained in the skeleton. When the need arises, calcium and other minerals can be mobilized from the skeleton and ' used for other body functions. Examples are the removal of calcium for milk production after a heifer or cow calves. GENETICS AND HEREDITYModern genetics began to develop very rapidly in the second decade of the 20th century though the foundation of it was laid by Gregor Mendel between 1857 and 1865. Since that time1 geneticists in all parts of the world have cooperated in establishing the chromosome theory of heredity. Usually the chromosomes of a given species are individually distinguishable, and exactly the same set appears at mitosis in all cells of the individual and of the species. The chromosome number varies in different organisms from 2 to 200 or more, but usually it is below 50 (man has 46). Not only the number of chromosomes but also the size and shape of each chromosome remain constant. Each chromosome carries a specific group of hereditary determinants - the genes. These carry coded instructions by means of which each cell is enabled to fulfil the destinies of its own parfaticular lineage. Chromosomes contain DNA, RHA and protein, and these constitute the genetic material of the cell. There are two chromosomes concerned in sex determination and they are not completely homologous. The male carries two chromosomes for sex called X and Y. The female carries two X chromosomes. The factor that determines whether the offspring shall be male or female is the presence of a Y or an X chromosome in the male gamete. Some knowledge of the substances concerned in transmission of hereditary factors has been gained in the last 40 years. We know that a gene is very small. Experiments have shown that there are about 10 000 genes carried on the chromosomes of Drosophila, commonly called the fruit fly. The search for human genes has only begun. The estimated number of genes in human DNA is 100 000. Each gene is found in the nucleus of every one of the human body's 100 trillion cells with the exception of red blood cells, which have no nuclei. And each gene is responsible for the manufacture of a particular protein that contributes to either the structure or the functioning of the body. Fewer than 2000 genes have been assigned to approximate location on chromosomes. Armed with the ability to cut, splice and transplant genetic material, scientists set to work deciphering the estimated 100000 genes tucked into the nucleus of virtually every human cell. Collectively, genes comprise the complete set of chemical instructions for making a human body. Each gene codes for the production of a single polypeptide (a protein component). Thousands of proteins give the human body function and form. If the gene is defective, protein synthesis will be faulty and a deformity or genetic disease will result. More than 4000 inherited disorders are due to single-gene defects. Many more are thought to be influenced by multiple genes or by a combination of genes and environment. Locating a specific disease-associated gene on one of 46 chromosomes - the genetic material inherited in equal parts from each parent - gives researchers the basis for a diagnostic test. With gene in hand, it may also be possible to identify the protein for which it codes, – a giant step toward understanding the disease and developing treatment for it. |
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