Scientific experiments that change the world (I)

Modern science flourished in many fields with many achievements in the fields of physics, chemistry, geography, astronomy, biology, medicine, genetic engineering, ecology and other industries. social science.

>>>Science experiments change the world (II)

Reviewing scientific experiments over the past few hundred years has had a strong impact and changed the face of the whole world.

Darwin and the flowers

This butterfly's long red hose is 'designed' to attract nectar and help pollinate a long-stemmed orchid.

Darwin is considered to be the first to recognize the importance of flowering plants (also known as angiosperms). They account for most of the total number of plants present on the earth. They dominate the ecosystem and are a major source of food for humans in the form of grains, rice or wheat.

Although he was the discoverer of 'Evolutionism' - one of the greatest inventions in human history, Darwin himself once had to say that the evolution of flowers is a difficult mystery. bear.

His scientific work 'Evolutionary Theory' was born starting from an expedition and survey on the HMS Beagle, a five-year round the world from England, to South America, the Pacific, Australia, The Indian Ocean, South Africa and finally return to England. After returning to England, he performed many observations and studies focused on orchids.

When planting and conducting research on some native orchids, Darwin found that their complex shape is an adaptation that allows them to attract insects that help them carry pollen to the neighboring flowers.

Darwin used the data collected when observing the corresponding species of orchids and pollinators to reinforce his natural selection theory. Three years later he described the natural selection phenomenon for the first time in 'Origin of Species'. Thus, it can be said that he has laid the foundation for studying the evolution of the species on the earth only through a few experiments on flowers.

Decoding the molecular structure of DNA

Alfred Hershey in the laboratory.

Although James Watson and Francis Crick were honored with the co-discovery of the structure of the DNA molecule, their work is largely based on previous studies by Alfred Hershey and Martha Chase. In 1952, Alfred and Chase performed a famous experiment, the results of this experiment showed that it is the DNA molecule that is the structure that carries the genetic information (not the protein).

After this discovery, other scientists began studies focusing on DNA molecules and its structural decoding. Rosalind Franklin used X-ray diffraction techniques to study DNA molecules and discovered twisted X-shaped structures; Franklin's work confirms the double-twisting structure and also notes the symmetry of the molecule, especially given that the two circuits run in opposite directions in the opposite direction.

Watson and Crick are greatly supported by these findings; later, Watson asked Franklin to cooperate to win another team in the race to find the structure of the DNA molecule, but she refused. Then, with the help of other colleagues, the two quickly completed the model of DNA molecular structure and published it before Franklin published any of her works.

Vaccination

Dr. Edward Jenner injected the first smallpox vaccine for young boy James Phipps on May 14, 1796.

The creation of the world's first vaccine is linked to the name of Edward Jenner, an English doctor. In 1796, when Europe had a smallpox epidemic, Jenner had successfully tested the vaccine against the disease. At that time, folk experiences showed that cows milking farmers could get cowpox, but after they recovered, they became immune to smallpox.

Based on that, Dr. Jenner took the fluid from cowpea on the arm of the patient Sarah Nelmes and implanted it into the arm of a healthy 8-year-old boy named James Phipps. Phipps then had symptoms of cowpea. 48 days later, Phipps got out of cowpea, Jenner immediately injected Phipps with smallpox, but Phipps did not suffer from the disease again. Jenner's approach to ethical standards today is not right, but it is obviously a groundbreaking action: the immunized child is resistant to the disease.

80 years later, Louis Pasteur performed some experiments on chickens and confirmed Jenner's hypotheses, thereby paving the way for modern immunology.

Vaccination has repelled many dangerous diseases: eliminating smallpox worldwide, paying almost completely polio, significantly reducing measles, diphtheria, whooping cough, rubella, chickenpox , mumps, typhoid and tetanus, . People also aim to use vaccines to treat some serious diseases like cancer, AIDS, .

The atomic nucleus was discovered

Ernest Rutherford is a New Zealand physicist who works in the field of radiation and atomic construction. He is considered the "father" of nuclear physics. He discovered that atoms have a positive charge concentrated in the atomic nucleus, thereby laying the foundation for him to develop an atomic planet model. Thanks to this discovery, plus the elucidation of Rutherford scattering in the experiment with gold foil, he received the Nobel Prize in chemistry in 1908.

Rutherford's atomic model was the first model to propose a tiny nucleus at the center of the atom, which could be considered the birth of the concept of atomic nuclei. After this discovery, the study of atoms was split into two branches, nuclear physics studied on atomic nuclei, and atomic physics studied the structure of electrons flying around.

However, the Rutherford model has a classic view of electrons flying in orbit like planets orbiting the Sun; cannot explain the orbital structure of electrons in relation to chemical processes; In particular, it does not explain why atoms exist in stable equilibrium and electrons do not fall into the nucleus. This model was then replaced by a semi-classical model of 1913 Neils Bohr and the quantum model of atoms.

Although it was inaccurate, Rutherford's atomic model was often used in illustrations in mass media as a symbol for atoms. For example, this model is drawn on the International Atomic Energy Agency flag.

X-ray crystallography industry

Although diamonds (top, left) and graphite (top, right) are similar in chemical composition (made entirely of carbon) but X-ray crystallography shows the arrangement of different atoms leading to differences in properties between them.

In diamonds, carbon atoms are arranged in tetrahedral blocks and held together by a single covalent bond, making it strongly connected in all directions. In contrast, structural graphite swims on overlapping layers, in which carbon atoms link hexagonally with single and double bonds, without covalent bonds between layers.

X-ray crystallography is the science that determines the arrangement of atoms within a crystal based on data on the dispersion of X-rays after shining on the electrons of the crystal.

Above we have mentioned the X-ray diffraction technique that Rosalind Franklin used to study the structure of DNA molecules; and the pioneer in using this technique is Dorothy Crowfoot Hodgkin, one of the only 3 women to win the Nobel Prize in Chemistry.

By projecting X-rays on the crystal to store on film the diffraction points caused by interference between the atoms of the crystal, then use the operations to calculate the distance and position of the specified points, Since then, the molecular structure of the crystal has been discovered, Dorothy has brought crystal studies to the results that scientists expect.

Beginning with the study of the structure of pepsin, an enzyme in the salivary glands, Dorothy successfully decoded the structure of cholesterol, lactoglobulin, ferritin, the structure of tobacco mosaic virus. In 1946, she announced the complex structure of penicillin antibiotics. Ten years later, she successfully decoded the structure of vitamin B12. In 1969, thanks to her research, insulin was no longer a headache for scientists.

It is hard to say which Dorothy contribution is more important than the contribution. If clarifying the B12 structure gave her the Nobel Prize in chemistry by B12 as a dark vitamin needed to help prevent pernicious anemia, then the success of penicillin's structure is open. For pharmaceutical companies the ability to produce semi-artificial penicillin helps solve the situation of scarcity of antibiotics at that time. Finding out the three-dimensional structure of insulin, an indispensable hormone in the body's metabolism, has contributed to maintaining the lives of tens of millions of people with diabetes worldwide.