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Gregor Mendel
Gregor Mendel the "Father of Genetics" performed an experiement in 1857 that led to increased interest in the study of genetics. Mendel who became a monk of the Roman Catholic church in 1843, studied at the University of Vienna where he mastered mathematics, and then later performed many scientific experiments. The greatest experiment that Mendel performed involved growing thousands of pea plants for 8 years. He was forced to give up his experiment when he became abbot of the monastery be -
1920s – Blood Typing
In the early 1900s, scientists identified 4 different blood types in humans – A, AB, B, and O – based on the presence of certain proteins called antigens in the blood. This blood typing system, called the ABO system, provided doctors with crucial information about their patients, allowing them to safely perform medical procedures, especially blood transfusions, by matching the blood types of patients and donors. In the 1920s, scientists recognized that blood types were genetically inherited. A -
Frederick Griffith
In 1928 a scientist named Frederick Griffith was working on a project that enabled others to point out that DNA was the molecule of inheritance. Griffith's experiment involved mice and two types of pneumonia, a virulent and a non-virulent kind. He injected the virulent pneumonia into a mouse and the mouse died. Next he injected the non-virulent pneumonia into a mouse and the mouse continued to live. After this, he heated up the virulent disease to kill it and then injected it into a mo -
1930s – Serological Testing
n the 1930s, scientists discovered other proteins in the blood that could be used for identifying humans. The Rh, Kell, and Duffy blood group systems, like the ABO system, were based on the presence of specific antigens in the blood. These antigens are also genetically inherited, proving useful in identifying possible biological relationships. Through these serological tests, scientists could use the blood group systems of two parents to predict the possible blood group of their child. Scienti -
Erwin Chargaff
To understand the DNA molecule better scientists were trying to make a model to understand how it works and what it does. In the 1940’s another scientist named Erwin Chargaff noticed a pattern in the amounts of the four bases: adenine, guanine, cytosine, and thymine. He took samples of DNA of different cells and found that the amount of adenine was almost equal to the amount of thymine, and that the amount of guanine was almost equal to the amount of cytosine. Thus you could say: A=T, and -
Oswald Avery
Fourteen years later a scientist named Oswald Avery continued with Griffith’s experiment to see what the inheritance molecule was. In this experiment he destroyed the lipids, ribonucleic acids, carbohydrates, and proteins of the virulent pneumonia. Transformation still occurred after this. Next he destroyed the deoxyribonucleic acid. Transformation did not occur. Avery had found the inheritance molecule, DNA! -
Rosalind Franklin and Maurice Wilkins
Two scientists named, Rosalind Franklin and Maurice Wilkins, decided to try to make a crystal of the DNA molecule. If they could get DNA to crystallize, then they could make an x-ray pattern, thus resulting in understanding how DNA works. These two scientists were successful and obtained an x-ray pattern. The pattern appeared to contain rungs, like those on a ladder between to strands that are side by side. It also showed by an “X” shape that DNA had a helix shape. -
James Watson and Francis Crick
In 1953 two scientists, James Watson and Francis Crick, were trying to put together a model of DNA. When they saw Franklin and Wilkin's picture of the X-ray they had enough information to make an accurate model. They created a model that has not been changed much since then. Their model showed a double helix with little rungs connecting the two strands. These rungs were the bases of a nucleotide (see nucleic acids). At first Watson and Crick were set back with a problem, how to bond the
