Text A Viruses1. For three-quarters

Text A Viruses

1. For three-quarters of a century, scientists have known that many diseases of man, animals, plants and even of microorganisms are caused by transmissible agents which cannot be seen under the light microscope, they are so small that they can pass through filters fine enough to hold back the most minute bacteria. These mysterious invisible agents were given the generic name of viruses. In the 1930's, two great discoveries were made which provided concrete informa- tion concerning the nature of viruses. It was found that some of them would be crystallized almost as readily as if they were ordinary chemical substances.

2. Chemically, the active virus particles were found to behave like giant molecules. At about the same time, the electron microscope became available and permitted pictures to be obtained of these crystals as well as of particles present in fluids and other materials having virus activity. Viruses would now be seen as concrete objects instead of being merely imagined.

3. The first unexpected fact revealed by electron microscopy was that the various viruses differ among themselves in shape and in size, as various types of bacteria. The virologist can differentiate between several types of viruses on the basis of their size and shape as revealed by electron micrographs. For example, the vaccinia virus is rather large. In contrast, the polioviruses are much smaller and yield very characteristic crystals. As to the tobacco mosaic virus, it can be crystallized in the form of thin needles having different lengths. The viruses that attack bacteria, which are called bacteriophages, are more complex, at least in

shape. Many of them have a thin tail and a large round or cylindrical head. Each active virus particle consists of at least two very different types of structural components. One structure made up of nucleic acid, carries the genetic hereditary characteristics of the virus. Another, protein in nature, is thought to protect this genetic apparatus and to facilitate its transfer from one infected cell to another. For example, electron micrographs revealed that virus of tobacco mosaic consisted of an inner constituent of nucleic acid lodged within an outer coat, cylindrical in shape and made up of protein. The central structure, the core, should be compared to the nucleus of ordinary cells in higher organisms, which also contains large amounts of nucleic acid and also carries the genetic endowment. In fact, the nucleic acid core of this virus is its most essential constituent. However, proteins and nucleic acids are not the only structural components of active viruses. Certain viral particles have recently been shown to contain lipids as part of their essential structures. High-magnification electron micrographs will reveal furthermore that some of them possess a distinct membrane. If we examined the structure of some of bacteria under highmagnification electron microscope we should see that they possess a distinct membrane.

Результаты (английский) 1:

Text (A) Viruses1. For three-quarters of a century, scientists have known that many diseases of man, animals, plants and even of microorganisms are caused by transmissible agents which cannot be seen under the light microscope, they are so small that they can pass through filters fine enough to hold back the most minute bacteria. These mysterious invisible agents were given the generic name of viruses. In the 1930 's, two great discoveries were made which provided concrete informa-tion concerning the nature of viruses. It was found that some of them would be crystallized almost as readily as if they were ordinary chemical substances.2. Chemically, the active virus particles were found to behave like giant molecules. At about the same time, the electron microscope became available and permitted pictures to be obtained of these crystals as well as of particles present in fluids and other materials having virus activity. Viruses would now be seen as concrete objects instead of being merely imagined.3. The first unexpected fact revealed by electron belogurova was that the various viruses differ among themselves in shape and in size, as various types of bacteria. The virologist can differentiate between several types of viruses on the basis of their size and shape as revealed by electron micrographs. For example, the vaccinia virus is rather large. In contrast, the polioviruses are much smaller and yield very characteristic crystals. As to the tobacco mosaic virus, it can be crystallized in the form of thin needles having different lengths. The viruses that attack bacteria, which are called bacteriophages, are more complex, at least inshape. Many of them have a thin tail and a large round or cylindrical head. Each active virus particle consists of at least two very different types of structural components. One structure made up of nucleic acid that carries the hereditary genetic characteristics of the virus. Another, protein in nature, is thought to protect this genetic apparatus and to facilitate its transfer from one infected cell to another. For example, electron micrographs revealed that of tobacco mosaic virus consisted of an inner constituent of nucleic acid lodged within an outer coat, cylindrical in shape and made up of protein. The central structure, the core, should be compared to the nucleus of ordinary cells in higher organisms, which also contains large amounts of nucleic acid and also carries the genetic endowment. In fact, the nucleic acid core of this virus is its most essential constituent. However, proteins and nucleic acids are not the only structural components of active viruses. Certain viral particles have recently been shown to contain lipids as part of their essential structures. High-magnification electron micrographs will reveal furthermore that some of them possess a distinct membrane. If we structure the capability of some of bacteria under highmagnification electron microscope we should see that they possess a distinct membrane.

Результаты (английский) 3:

text a Viruses

1. for three quarters of a century, with have known that many diseases of man, animals, plants and even of microorganisms are caused by transmissible agents which cannot be seen under the light, which are so small that they can pass through filters fine enough to hold back the most minute bacteria.these mysterious invisible agents were given the generic name of the viruses. in the 1930's, the two great discoveries were made which provided concrete informa - tion concerning the nature of viruses. it was found that some of them would be crystallized almost as philology as if they were ordinary chemical substances.

2. Chemically, the active virus particles were found to behave like giant molecules.at about the same time, the electron, became available and their pictures to be obtained of these crystals as well as of particles present in fluids and other materials having anti-virus activity. Viruses would now be seen as concrete objects instead of being merely imagined.

3.the first big fact been by electron microscopy was that the various viruses differ among themselves in shape and size, and the various types of bacteria. the virologist can differentiate between several types of viruses on the basis of their size and shape as been by electron micrographs. for example, the vaccinia virus is rather large. in contrast,the polioviruses are much smaller and yield very characteristic crystals. as to the tobacco mosaic virus, it can be crystallized in the form of thin needles having different lengths. the viruses that attack bacteria, which are called bacteriophages, are more complex, at least in

shape. many of them have a thin tail and a large round or cylindrical head.each active virus particle consists of at least two very different types of structural components. one structure made up of nucleic acid, hereditary carries the genetic characteristics of the virus. another, protein in nature, is thought to protect the genetic apparatus and to facilitate its transfer from one infected cell to another. for example,