Category Great Scientific Discoveries

         “You look exactly like your mother!” “Like father like son.” Most of us might have heard comments like these. It is true that we resemble our parents. But why is it so? Because we inherit certain traits from them.

          The fundamental laws of inheritance were discovered by Gregor Mendel. Through his work on pea plants, he deduced that genes come in pairs and are inherited as distinct units, one from each parent. For example, a man and a woman both with brown eyes could have a one-in-four chance of producing a child with blue eyes. Mendel published his discoveries in 1865 after spending eight years doing genetic experiments on pea plants. However, his work was disregarded by a vast majority.

          It was Dutch botanist Hugo De Vries who realised the importance of Mendel’s discoveries in 1900. Many rules of heredity were established by Mendel’s experiments and are now referred to as the laws of Mendelian inheritance. He gained recognition as the founder of the modern science of genetics posthumously.

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          There is a lot of confusion as to who actually discovered DNA. Though many give credit to James Watson and Francis Crick for discovering DNA in the 1950s, the actual discovery occurred decades before that.

          Watson and Crick came to their monumental conclusion about the structure of DNA in 1953 by building up on the work of pioneers before them.

          The molecule now known as DNA was first identified in the 1860s by the Swiss chemist, Johann Friedrich Miescher who called it ‘nuclein’.

          Although the significance of this discovery was not initially recognised, it set further research and discoveries in motion. In the 1880s, Albrecht Kossel isolated the five organic compounds that are present in nucleic acid: adenine, cytosine, guanine, thymine and uracil. The role of DNA in heredity was confirmed in 1952, when Alfred Hershey and Martha Chase showed through experiments that DNA is genetic material.

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          Fingerprints have been found on ancient Babylonian clay tablets. They are excellent in establishing the identity of individuals and hence widely used to track down criminals. However, this is only possible because they have been systematically classified, making it easy to compare new prints with the ones on record.

          British scientist Francis Galton devised a basic classification after confirming that every fingerprint is different. Galton estimated that there is only 1 in 64 billion chance of a false positive, which happens if two individuals have the same fingerprint. An Argentine police officer named Juan Vucetich created the method of recording the fingerprints of individuals on file by studying Galton’s pattern types. He set up the world’s first fingerprint bureau in 1892.

          A fingerprint bureau was established in Kolkata in 1897. Azizul Haque and Hem Chandra Bose were the two fingerprint experts in Kolkata. They co-devised a system that became popular. It was named the Henry Classification System, after their supervisor Edward Henry.

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          When people recover from bacterial illnesses, they often develop antitoxins that give them immunity against recurrence of the disease. An antitoxin is an antibody with the ability to neutralize a specific toxin.

          One of the most popular antitoxins is the diphtheria antitoxin. In 1888, Emile Roux and Alexandre Yersin showed that the toxins produced by the Corynebacterium diphtheriae causes symptoms of diphtheria in animals. Two years later, the first antitoxin to diphtheria was made when Shibasaburo Kitasato and Emil von Behring immunised guinea pigs with heat-treated diphtheria toxin. Behring received the Nobel Prize for Physiology or Medicine in 1901.

          It is believed that the diphtheria antitoxin was first used to treat a diseased human in 1891. Today antitoxins are used in the treatment of botulism, diphtheria, dysentery, gas gangrene and tetanus.

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          Russian microbiologist Dmitry Ivanovsky was the first to realize that bacteria were not the only infective agent. Ivanovsky published a paper on a virus infection of tobacco plants in 1892. However, lvanovsky probably did not grasp the full meaning of his discovery. Martinus W. Beijerinck, in 1898 became the first one to use the term ‘virus’ to indicate the microorganism causing tobacco mosaic disease.

          A virus is an infectious particle that can multiply only inside a living cell. Since it is made of only a set of genes wrapped in protective covering, a virus takes over a plant or animal cell and forces it to replicate the invader. Both lvanovsky and Beijerinck discovered that viruses were smaller than bacteria and invisible under an ordinary microscope. These two scientists brought significant and complementary contributions to the discovery of viruses. The discovery of tobacco mosaic virus stands out as a milestone in the history of virology.

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          Many aspects of the human body remained unclear to us till the advancement of medical science. The reason why certain blood transfusions were successful while others could be deadly was discovered only in 1900 by Karl Landsteiner at the University of Vienna. He discovered the ABO blood group system by mixing the red cells and serum of each of his staff. Landsteiner demonstrated that serum of some people agglutinated or caused clumping of red blood cells of others.

          From these early experiments, he identified three blood groups which he called A, B, and C. The last one was later renamed ‘O’ from the German term ‘Ohne’ which means ‘without’, similar to ‘zero’ or ‘null’ in English.

          The fourth blood group AB, which is rarer than the others, was discovered a year later. Landsteiner was awarded the Nobel Prize in Physiology or Medicine in 1930 for his work.

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