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GENETIC MATERIAL(Replication, Transcription, Translation) 1st part........

Genetic material governs the inheritance of traits from one generation to the next as well as it is able to express its effects through the formation and functioning of the traits. It stores biological information in the coded form. The genetic material should have the following characteristics : 1. It should be able to precisely duplicate itself, forming its carbon copies. This is called replication. 2. It should be able to faithfully pass its copies into the progeny. 3. It should be able to occasionally undergo mutations to allow adaptation and evolution to occur in the organism. 4. It should be able to store information in the coded form for the control of biological functions of the cells. 5. It should be able to express its information in the progeny. In addition to all these characteristics, genetic material should be present in every cell and it should show diversity. There was a lot of controversy about the nature of genetic material. Earlier proteins were considered as the gen...
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PLANT DISEASES

A large number of diseases occur on various crops. These diseases may be caused by fungi, bacteria, viruses and other pathogensStem rusts, white rusts, smuts, blights, wilts downy mildews, powdery mildews, cankers etc. are of the important diseases. Symptoms, causal organisms, etiology and control measures of some of the more common diseases are discussed in this chapter. DISEASES CAUSED BY FUNGI 1. LATE BLIGHT OF POTATO Late blight of potato was initially an endemic disease of South America. Because of quick transportation this disease spread to U.S.A. and Europe in 1830-1840. This disease caused famous Irish Famine in 1845-1846 where it caused havoc in potato fields and completely destroyed the potato crop andresulted in the death and migration of millions of people. In India the disease first appeared in Nilgiri hills between 1870-1880. Then it was reported from Darjelling. Because of high temperature in the plains, the disease did not appear in the plains of India. It appeared for ...
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Cell Reproduction

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All the living organisms are composed of cells. They grow and reproduce. The growth and development of every living organism depends upon the growth and multiplication of the constituent cells. Unicellular bacteria which are minute and microscopic, alligators and the weeds which are giant sized, produce offspring like themselves and pass on to them the hereditary information that makes them what they are. In unicellular organisms, cell division is the of reproduction. Multicellular organisms develop from a single cell, the zygote, which is formed by the fusion of preceding cells, the gametes. The ways by which new cells originate have been thoroughly investigated, only after 1846 when Nageli pointed out that new cells are always formed through the division of pre-existing cells. Rudolf Virchow (1855) supported the above idea and investigated the process of cell division. R. Virchow gave the first modifcation of cell- theory. He gave the statement 'Omnis cellulae cellula', which...
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BIOLOGY----- A SCIENCE OF EXCEPTIONS...

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The laws that govern the physical and chemical phenomena of non-living bodies are rigid and no deviations or exceptions are noticed. Although, physical and chemical phenomena are associated with life processes, the laws of physical and chemical phenomena are not always followed in their true sense, because, life-forms exhibit enormous variations and adaptations in their functions. Life-forms are constantly evolving and changing in forms and functions to get advantage. As a result of this, variations in the laws that govern the phenomena of life functioning are observed.Therefore, biologist must be prepared to accept exceptions of laws and principles.                 Some examples of such exceptions are given below: 1. Euglena has both plant characters as well as animal characters. They lack cell wall, but bear chloroplasts. 2. Viruses do not observe definite set rules of living being. 3. Mangrove produces respiratory roots (pneuma...
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Chromatography.

Chromatography is applied for separation of one or more biological compounds from a mixture of such compounds. Chromatography is based on two phases of the compounds. One is the stationary phase and the other is the mobile phase. The stationary phase may be solid, gel, liquid or solid liquid mixture. The mobile phase may be liquid or gases which flow over the stationary phase. In paper chromatography, the cellulose fibres of, the paper is the stationary phase, in thin layer cromatography, the thinly coated gel on plate is the stationary phase and in column chromatography, the packed glass or metal column acts stationary phase. The differential solubility ability of the individual compounds in the stationary and mobile phase is the basis of separation of compounds. The specific solvents solublise the compounds and when it moves along the stationary phase it carries with it the compounds of differential solubility. The ratio of the distance travelled by the solvent and the compounds of d...
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GROWTH OF SCIENTIFIC KNOWLEDGE

There is no such claim in the science that every natural phenomenon has been discovered and fully analysed. There are certain fields of science where knowledge is only preliminary. Knowledge about scientific phenomena has been increasing day by day. There is nothing like 'ultimate truth'or final proof. Everything is likely to get changed with new findings of research. Science does not believe in God and in supernatural powers. Rather, it deals with natural phenomena. Religion and science should not be mixed. Religion is a matter of faith and faith cannot be verified or can not be put to experimentation. Careers to Biologists There are so many disciplines closely related to biology. With a sound background and good knowledge of biology one can choose any one of the following fields :-- 1. Anthropology—The science of man and mankind. 2. Agronomy--Management of  crop production. 3. Pathology-The science concerning various diseases, their causes, symptoms, effects and control measu...
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IMAGES OF COMPOUND MICROSCOPY

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