My Science School

           Hormones are chemicals such as adrenaline, which control our body and cause our heart to pound in times of stress.

            The first hormone was discovered in 1902 by William Bayliss and Ernest Starling, two British physiologists (people who study how living things work). They found that when food reaches the stomach, a chemical is released into the bloodstream, making the pancreas secrete digestive juices. They called this chemical secretin. The term ‘hormone’ was later coined by Starling. It is derived from the Greek expression meaning ‘setting in motion’.

            Physiology made a great leap when Bayliss and Starling introduced the concept of hormone with recognition of chemical regulation three years later. Even today, our understanding of hormones is a work in progress.

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            Before the use of antibiotics, sulphonamides were the only drugs that could kill a wide range of bacteria. In 1932, German bacteriologist Gerhard Domagk discovered the first prontosil, a non-antibiotic anti-bacterial drug. Scientists later realized that this broke down in the body to give a more potent drug, sulphanilamide.

            From 1936, after clinical trials by British doctor Leonard Colebrook, several sulpha drugs were used to save thousands of lives. They are still used when antibiotics are ineffective. For his remarkable achievements in the fight against infections, Domagk received the Nobel Prize for Medicine in 1939.

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            Our body requires vital elements including carbohydrates, proteins, minerals, fats and vitamins. The discovery of vitamins was a major scientific achievement in our understanding of health and diseases. Research flourished between early 19th century and mid-20th century resulting in plenty of discoveries.

            British biochemist Frederick Hopkins conducted an experiment on rats by feeding them an artificial mixture of the known constituents of milk such as carbohydrates, proteins and fat. He found that rats died when they were fed the mixture of these ingredients, but thrived when fed real milk. Hopkins concluded that to grow, animals need another substance in their diet that was described as accessory factors.

            In 1912, Polish biochemist Casimir Funk identified one of these in rice. On finding that it was a chemical called an amine, he proposed the name ‘vita mine’. Though all vitamins are not amines, the name Funk suggested was adopted after removing the ‘e’ from the end.

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          The assumption that the nucleic acid in DNA carries genetic information was proved by Oswald Avery by 1943. However, no one could explain how it worked. By the early 1950s, two groups of scientists were on the verge of a breakthrough regarding this.

          At King’s College in London, Rosalind Franklin and Maurice Wilkins were studying DNA using X-ray diffraction as the primary tool. James Watson and Francis Crick however, made crucial advance by proposing that the DNA molecule was made up of two chains of nucleotides paired to form a double helix, like a spiral staircase.

          The double helix structure of DNA was discovered by Watson and Crick in 1953. Double helix refers to the structure formed by double-stranded molecules of nucleic acids and this structure was first published in the journal Nature in 1953.

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          Poliomyelitis or polio is a viral infection that can cause paralysis. It remained a widespread threat until the US physician Jonas Salk developed polio vaccine. It was first successfully used at a trial in 1952 and the Salk vaccine finally received approval in 1955 after further trials.

          The more commonly used vaccine against polio that is administered orally was developed by a Polish-US physician Albert Sabin. The vaccine contains weakened polio virus that builds immunity without harming the body. As one of the most necessary medications required in a basic health system, it has been added to WHO’s list of essential medicines.

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          Oncogenes are genes with the potential of causing cancer. Human oncogenes were first discovered by multiple US research teams in 1981. One research team consisted of Prof. Robert Weinberg at the Centre for Cancer Research which is part of the Massachusetts Institute of Technology. Another one was that of Dr. Geoffrey Cooper at the Sydney Farber Cancer Institute, in Boston.

          Oncogenes do not generate cancer by themselves, but do so under the influence of carcinogens, or ionising radiations. Research has isolated cancer genes associated with cancer of different parts like colon, bladder, and kidneys.

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                                                                                                    The link between AIDS and HIV was established in 1983. Human Immunodeficiency Virus (HIV), identified in the 1980s is a group of viruses called retroviruses. Available evidence shows that it affected humans sometime in the late 19th or early 20th century during hunting and butchering of primates. A particular type of chimpanzees in West Africa has been established by scientists as the source of HIV infection in humans.

                The earliest known case of HIV-1 infection of a human was found in 1959 from the blood sample of a man from Kinshasa, Democratic Republic of the Congo.

                Identifying and diagnosing HIV is the first step in availing proper treatment. Implementing identification strategies are crucial to improve quality of life of infected individuals and reduce infant and child mortality due to HIV, particularly in sub-Saharan African nations and all around the world.

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          Dolly is the first mammal to be cloned from an adult cell and this made her the world’s most famous clone. A clone has the same DNA sequence as its parent and therefore, it is genetically identical. Researchers claimed that they had used a mammary gland cell for cloning Dolly.

          In the previous attempts at cloning of animals such as frogs, mice, and cows, DNA from embryos had been used.

          Dolly was cloned at the Roslin Institute in Scotland and lived there until her death in 2003 at the age of six.

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             The human genome is a human being’s complete set of genes contained within a sequence of chemical units (adenine, cytosine, guanine or thymine) unique to humans. At present, no human genome has been sequenced completely.

              A draft of the genome sequencing was announced by two rivals- the public Human Genome Project (HGP) led by Francis Collins, and the private Celera Genomics, led by Craig Venter- on 26 June 2000. Neither of these genome sequencing projects was completed. HGP has progressed lesser than the other but permits the public to see their result free of cost whereas, Celera charges people for access. As of February 2004, relatively more information was published by both organizations.

                 Though the work is not complete, researchers have sequenced over a million human genomes by late 2018.

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          The quest to find indivisible particles of matter started as early as 450 BC with the Greek philosopher Democritus. He wondered what would happen if one kept on cutting an apple into smaller pieces. He named those final pieces which could not be cut anymore ‘atomos’. The modern name atom comes from this.

          British Chemist John Dalton revived the ideas of Democritus in the1800s. He developed Dalton’s atomic theory from his research. It states:

a) All substances are made of atoms.

b) Atoms are the smallest particles of matter which cannot be divided further.

c) Atoms can neither be created nor be destroyed.

d) All the atoms of element are alike and have the same mass. Atoms of different elements have different masses.

e) Atoms join together to form compounds and a given compound always consists of the same kinds of atoms in the same ratio.

          Dalton’s theory was accepted worldwide. However, Dalton’s idea that atoms are the smallest particle was disproved with the discovery of protons, neutrons and electrons.

 

          Methanol also known as methyl alcohol, wood alcohol, or wood spirit was formerly produced by the destructive distillation of wood, that is, the decomposition of wood by heating it in the absence of air.

          It has been in use since ancient times. For instance, methanol obtained from wood was one of the different substances used by ancient Egyptians for embalming. This clear, flammable, and toxic liquid can cause blindness, if repeatedly inhaled or ingested.

          The older names for methanol such as spirit of wood and wood alcohol came into use because it is a by-product of distillation of wood, a process discovered by an Irish chemist named Robert Boyle. He synthesised pure methanol in 1661.

          Nowadays, carbon monoxide gas is combined directly with hydrogen in the presence of a catalyst for methanol preparation. However, syngas, which is a mixture of hydrogen and carbon monoxide derived from biomass, is more commonly used for methanol production.

          Pure methanol is an important material in chemical synthesis. It is used in rocket fuel and added to fuel mixtures to stretch the life of gasoline.

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          In 1669, a chemist named Hennig Brand in Germany prepared a luminous substance from urine. He called it ‘cold fire’ as it glowed in the dark. This substance was phosphorus.

          The name phosphorus is derived from the Greek word ‘phosphoros’, which means “bringer of light.”

          Like other non-metals, pure phosphorus can assume different forms. There are several phosphorus allotropes. Four common forms are white, red, violet, and black phosphorus. Brand had discovered white phosphorus. He was extremely secretive about the method he used to produce phosphorus from urine. Ultimately, he sold the recipe to D. Krafft, a commercial agent from Dresden, Germany. A few years later, Johann Kunckel in Sweden managed to make phosphorus. Robert Boyle in London followed suit.

          The forerunner of modern matches was first introduced by Robert Boyle who used phosphorus to ignite sulphur-tipped wooden splints in 1680.

          Phosphorus is essential for life. It is a component of DNA, RNA, ATP, and phospholipids. Phosphate also serves as a great fertilizer.

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          Carbon dioxide was the first gas to be identified as a component of the air around us. Its effects were observed long before scientists understood the function of carbon dioxide.

          Around 1640, the Flemish scientist Jan Baptist van Helmont discovered that air was not composed of a single substance as previously understood and there were vapours different from air. He coined the term ‘gas’ to describe these vapours.

          The gas given off by burning wood was collected, and Helmont called it ‘gas sylvestre’. It was later understood that this gas was carbon dioxide.

          A more substantial study of carbon dioxide was done by the British chemist Joseph Black through systematic investigation. In 1756, Black discovered that heating carbonates resulted in the release of carbon dioxide. In 1783, French physicist Pierre Laplace demonstrated that oxygen from the air is used to burn carbon stored in the body and produce the carbon dioxide in exhaled breath.

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          Robert Boyle had synthesized hydrogen gas while experimenting with iron and acids in 1671.

          However, it was recognized as a distinct element only in 1766 by Henry Cavendish. Hydrogen gas was produced when Cavendish dissolved metal in sulphuric acid. He first found that hydrogen is lighter than any other gas. Later, he confirmed that hydrogen forms water when it burns. This property inspired the French chemist Antoine Lavoisier to use the Greek term ‘hydrogen’ which means ‘water maker’ to describe it.

          Found abundantly in living matter, plants and animals, hydrogen is one of the most important elements. Hydrogen is found almost everywhere.

          We have it all around us in the form of water, fats and proteins. But it is also found in stars and giant planets. Even the sun is mostly made up of hydrogen. Inside the sun and other stars, hydrogen atoms are converted to helium atoms due to intense pressure. This process is called fusion.

          Hydrogen is used to make ammonia for fertilizers. In rocket fuel, liquid hydrogen is combined with liquid oxygen to produce a powerful explosion.

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