Earth Science: Chemistry – Organic and biochemistry – Nucleic Acids: Molecular Building Blocks
Our sex, the color of our eyes, and all other characteristics are stored in our hereditary material. This task is handled by four molecules: adenine, cytosine, guanine, and thymine.
Up to about 150 years ago, scientists believed that hereditary information was stored in proteins. It was not until 1869 that the Swiss physiologist Friedrich Miescher (1844-1895) discovered a whitish sub- stance in white blood cell nuclei. Since it differed from proteins, he referred to it instead as nuclein.
Twenty years later the biochemist Albrecht Kossel (1853-1927) wrote: “While digesting nucleins with diluted acids I have discovered a new base of general occurrence. This base, for which I suggest the name ‘Adenine, ‘ was pre- pared from the pancreatic glands of cattle” After this discovery, Kossel isolated another three molecules and verified they were related to the pentose carbohydrate ribose.
Building on this, his student, Hermann Steudel, discovered that each carbo- hydrate molecule bonded to a molecule of phosphoric acid. This meant that at the turn of the 20th century it was understood how the building blocks of hereditary material—the mononucleotides-were structured. Each nucleotide possesses a phosphate remnant to which carbohydrate bonds.
The carbohydrate is a deoxyribose (a ribose lacking an oxygen atom). One of the four bases-adenine, cytosine, guanine, or thymine—bonds to the deoxyribose. Due to the groundbreaking research of the Canadian bacteriologist Oswald Avery (1877- 1955), It was discovered that hereditary characteristics are transferred from bacterial cells by deoxyribonucleic acid (DNA).
Yet a mystery remained as to the connection between individual components of mononucleotides, and how they formed DNA. The Austrian-American biochemist Erwin Chargaff (1905-2002) discovered in 1952 that the bases adenine and thymine, as well as cytosine and guanine occurred in equal proportions. Afterward the English biochemist Rosalind Franklin (1920-1958) took ground-breaking x-rays of crystallized DNA.
The American biochemist James Watson and his British colleague Francis Crick used Chargaff’s and Pauling’s discoveries as well as Franklin’s x-rays, and re- solved the spatial structure of DNA, solving the puzzle of DNA and establishing the basis of modern gene technology.
DISCOVERY OF THE STRUCTURE OF DNA
The biochemists James Dewey Watson and Francis Harry Compton Crick, and biophysicist Maurice Hugh Frederick Wilkins, were awarded the Nobel Prize, for discovering the molecular structure of nucleic acids.
Rosalind Elsie Franklin, who contributed significantly to the discovery, had passed away four years earlier of cancer
BASICS
EVERY HUMAN has in his or her DNA certain unique traits These can be used to prove, through evidence. a suspect’s guilt in many cases of violent crimes.