Tina
Morgan was born in Lexington, Kentucky, on September 25, 1866, His uncle was a famous general of the Confederate Army during the American Civil War, so the Morgans were also respected by their neighbors. In his family, there were rich businessmen, soldiers, diplomats, and lawyers, but no scientists. To borrow current genetic terminology, Thomas Hunt Morgan can be regarded as a "mutation" product in the family.
He has done many interesting experiments in his life, but many of them ended in failure. Sometimes Morgan quipped that his experiments could be divided into three categories: the first category was stupid experiments, the second category was extremely stupid experiments, and there was a category that was more stupid than the second category. Although he failed repeatedly, but he never give up, because he knew that as long as there was a meaningful experiment in scientific research, all his efforts would be rewarded.
After Mendel's genetic research was rediscovered in 1900, new information about genetics was constantly spread to Morgan's ears. Morgan doubted Mendel's theory and chromosome theory. He raised a very sharp question: the sex of living things must be controlled by genes. So, is the gene that determines sex dominant or recessive? Morgan, who loved science, began to experiment because of this suspicion. In his experiment, he chose drosophila (highly fertile) as the experimental object.
The drosophila flies in the experiment were tortured by Morgan. They were irradiated by X-ray, laser, sugar, salt, acid and alkali at different temperatures, and even prevented from sleeping. Various methods have been used to induce mutation in Drosophila melanogaster. But two years later, this batch of fruit flies did not produce the results he wanted. One day Morgan found an abnormal white eyed male fruit fly among the red eyed fruit flies. He had never seen such a fruit fly before, so this one was a rare mutant. He was very excited. He took the mutant white eyed male fruit fly home and took good care of it. Finally, he got the white eyed fruit fly from the second generation of hybrid fruit fly. The offspring of this family are all red eyed. Obviously, red is dominant to white, which is exactly the result of Mendel's experiment. Morgan was surprised unconsciously. He made his offspring mate again, and found that the proportion of red and white fruit flies in the second generation was exactly 3:1, which was also Mendel's research result, so Morgan admired Mendel even more. Morgan decided to follow this clue and see how animals inherit. He further observed and found that the second generation of Drosophila melanogaster were all female, which indicated that the sex (male) factors of the trait (white) were linked together. When the cell division, the chromosome first changed from one to two, indicating that the trait could be inherited. The sex gene was on the chromosome, and it was passed down from generation to generation through cell division.
Chromosomes are the carriers of genes. Morgan and his students also calculated the positions on chromosomes of various genes, and drew the position map of genes arranged on four pairs of chromosomes of Drosophila. Gene theory was born, and the mystery of male and female gender was finally revealed. Since then, genetics has ended the era of fantasy. Major discoveries have followed, and it has become the most active research field in the 20th century. For this reason, Morgan won the 1933 Nobel Prize in Physiology and Medicine. "Linkage and exchange law" is Morgan's great contribution in the field of genetics. Together with Mendel's separation law and free combination law, it is called the three laws of genetics.
Comments