Thursday, July 29, 2010

Herd Technology

In order for an infectious disease to occur in epidemic form, the causative microorganism must be transmitted easily from one susceptible host to another within the population. Unless a sufficient proportion of the population is susceptible, the disease can occur only in an endemic or sporadic form. For instance, if 70 percent of Schoolchildren in a population are immunized against poliomyelitis, epidemics of this disease are unlikely to occur even among the remaining 30 percent who were not immunized. These latter children enjoy what has been termed herd immunity. This is not true immunity but merely an expression of the unlikelihood that a susceptible individual will encounter the causative agent of the disease


Being a French professor of Chemistry at the University of Lille, France, Louis Pasteur has got his brilliant career. The manufacture of wines and beer was the principal industry of France where Pasteur studied the method and processes involved in order to help his neighbors produce a consistently good product. He found that fermentation of fruits and grains, resulting in alcohol, were brought about by microbes. By examining many batches of "ferment," he found microbes of different sorts. In good lots one type predominated, and in the poor products another kind was present. By proper selection of the microbe, the manufacture might be assured of a consistently microbes might be removed by heating- not enough to hurt the microbial population. He found that holding the juices at temperature of 62.80c (1450f) for half an hour did the job. Today pasteurization is widely used in fermentation industries, but we are most familiar with it in dairy industry.


Short History

History is the story of the achievements of men and women, but it records relatively few outstanding names and events. Many important contributions were made by people whose names have been forgotten and whose accomplishments have been lost in the longer and deeper shadows cast by those who caught the fancy of the chroniclers. It has been said that in science the credit goes to the one who convinces the world, not to the one who first had the idea. So, in the development of microbiology, the outstanding names are often of those who convinced the world- who developed a technique, a tool, or a concept that was generally adopted, or who explain their finding so clearly or dramatically that the science grew and prospered.
The lucid report of Antony van Leeuwenhoek on the ubiquity of microbes enabled Louis Pasteur 200 years later to discover the involvement of these creatures in fermentation reactions and allowed Robert Koch. Theobald Smith, Pasteur and Many others to discover the association of microbes with disease. Koch is remembered for his isolation of the bacteria that cause anthrax and tuberculosis and for the rigid criteria he demanded before a specific bacterium be held as the cause of disease. His important contributions to the creation of the science of microbiology won him the 1905 Nobel prize.The building of Panama Canal dramatized Walter Reed's studies in the epidemiology of yellow fever. Theobald Smith work on transmission of Texas fever pointed the way for Walter Reed's subsequent work.

Tuesday, July 27, 2010

Fuel Biotechnology

The use of biological agents to convert relatively diffuse and inconvenient to use sources of energy, e.g., biomass and sunlight, into more energy-dense and convenient to use fuels, e.g., methane, ethanol, butanol, biodiesel and hydrogen, constitutes fuel biotechnology. Biomass is the total cellular dry weight or organic material produced by an organism (usually from CO2 and sunlight), while biologically produced fuels are usually called biofuels. In general, biofuels are aimed for use in transport as a substitute for the nonrenewable and rapidly declining fossil derived from petroleum. Biomass still contributes a large part (74%) of the energy needs of developing countries, while only about 2% of energy used by developed countries is directly obtained from biomass.


During early development, the egg cell undergoes repeated mitotic divisions in rapid succession. These lead to the addition in the number of cells in the zygote without adding to its size. i.e. there is no growth in cell.
The Cleavage can be defined as "the progressive subdivisions of the zygote by mitotic cell divisions into increasing number of cells of progressively decreasing size"

Pattern of cleavage

  • Right cleavage

  • Bilateral cleavage

  • Spiral cleavage


In mimicry the animal resembles or imitates some other animal, plant or other natural object not only in color but also in shape, size, appearance, surface structure and other details. Mimicry of spider is shown in figure. Mimicry can be classified as under.

  1. Protective mimicry.

  2. Warning mimicry.

  3. Aggressive mimicry

  4. Simulation of death.

  5. Terrifying appearance.

  6. Warning color.

  7. Warning signals.

RNA Metabolism

The RNA (Ribonucleic acid) of the cell is partly in the nucleus, partly in particles in the cytoplasm and partly as the "soluble" RNA of the cell sap; many workers have shown that all these three fractions turn over differently. It is very important to realize in any discussion of the role of RNA in the cell that it is very in homogeneous metabolically, and probably of more than on type. –Francis H.C. Crick, article in Symposia of the society for Experimental Biology. 1958.

Expression of the information in a gene generally involves production of an RNA molecule transcribed from a DNA template. Strands of RNA and DNA may seem quite similar at first glance, differing only in that RNA has hydroxyl group at the 2' position of the aldopentose, and uracil instead of thymine. However, unlike DNA, most RNA carry out their functions as single strands, strands that fold back on themselves and have the potential for much greater structural diversity than DNA. RNA is thus suited to variety of cellular functions.All RNA molecules except the RNA genomes of certain viruses are derived from information permanently stored in DNA. During transcription, and enzyme system converts the genetic information in a segment of double-stranded DNA into and RNA strand with a base sequence complementary to one of the DNA strands. Three major kinds of RNA are produced. Messenger RNAs (mRNAs) encode the amino acid sequence of one or more polypeptides specified by a gene or set of genes. Transfer RNAs (tRNAs) read the information encoded in the mRNA and transfer the appropriate amino acid to a growing polypeptide chain during protein synthesis. Ribosomal RNAs (rRNAs) are constituents of ribosome, the intricate cellular machines that synthesize proteins. Many additional specialized RNAs have regulatory or catalytic functions or are precursors to the three main classes of RNA.