Thursday, July 29, 2010
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.
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
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
- Protective mimicry.
- Warning mimicry.
- Aggressive mimicry
- Simulation of death.
- Terrifying appearance.
- Warning color.
- Warning signals.
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.
There are two fundamental conditions for life. First, the organism must be able to self – replicate; second, it must be able to catalyze chemical reactions efficiently and selectively. Without catalysis, chemical reactions such as sucrose oxidation could not occur on a useful time scale, and thus could not sustain life. Enzymes, a reaction catalysts of biological system is the most remarkable and highly specialized proteins, which have extraordinary catalytic power, often far greater than that of synthetic or inorganic catalysts. They have a high degree of specificity for their substrates, they accelerate chemical reactions tremendously, and they function in aqueous solutions under very mild conditions of temperature and pH. Few non-biological catalysts have all these properties.
Enzymes are central to every biochemical process. Action in organized sequences, they catalyze the hundreds of stepwise reactions that degrade nutrient molecules, conserve and transform chemical energy, and make biological macromolecules from simple precursors. Most of the enzymes are proteins.
"Catalysis can be described formally in terms of a stabilization of the transition state through tight binding to the catalyst." -William P. Jencks, article in Advances in Enzymology, 1975
(A short note)
These seven metals were:
1.) Gold (ca) 6000BC 5.) Tin, (ca) 1750BC
2.) Copper,(ca) 4200BC 6.) Iron,smelted, (ca) 1500 BC
3.) Silver,(ca) 4000BC 7.) Mercury, (ca) 750BC
4.) Lead, (ca) 3500BC
It is a kind of genetic engineering in which microorganism are genetically engineered with good strains of genome to obtain useful product like insulin, Hepatitis-B vaccine.
Gene therapy and Magic bullet mechanism is a recombinant DNA technology. Main application of recombinant DNA technology is :
- To produce new medicine & safer vaccines.
- Increase agricultural yields & decrease production cost.
- Treat some genetic disease like colourblindness.
- Maintain or Improve food's nutritional value.
- Maintain environment (i.e. decrase water and air pollution)
- Detect food spoilage ...etc.
Different species of Mushroom cultured with different technology. But one of the Oyster Mushroom cultured as follows:
- Cutting of paddy straw
- Soaking in water for 3-4 days
- Draining of water overnight
- Steaming of straw for surface sterilization
- Spawing on straw containing into polythene bags
- Incubate up to 3 weeks at 25 degree centigrate
- Mushroom primordial after 3-4 days of removal of polythene bags
- Mushroom, ready for harvest and market
The main purpose of mushroom culture is to provide food supplement to consumers.
In 1897, Email Fischer postulated a lock and key hypothesis to explain the interaction on between the enzyme molecule and substrate.
According to this model the activaste site of an enzyme is already exist in proper conformation even in the absence of substrate. The enzyme molecule itself provides a rigid, preshaped template fitting with the size and shape of the substrate molecule. The substrate fits into active site of an enzyme as key fixed into the lock and hence it is called as lock and key model but this model can not explain the change in the enzymatic interaction.