By AnnMarie Menish

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the branch of science concerned with the chemical and physical-chemical processes that occur within living organisms. This branch studies the chemical characteristics and reactions of a particular living organism or biological substance.

Rudolph Marcus

Born on July 21, 1923 in Montreal, Quebec, Canada. He was interested in sciences since a very young age. He actually more interested in mathematics which later extended to science after he excelled during his years at Baron Byng High School. He later went to the McGill University where he studied under Doctor Carl A. Winkler. Marcus earned a B.Sc in 1943 and a Ph.D in 1946 both from McGrill University. In 1958 he became a naturalized citizen in the united states. He is an active professor at Caltech and Nanyang Technological University in Singapore.

When he was younger Marcus always loved going to school. Since his parents didn't have a higher education his 'idols' were his two uncles. Marcus grew up in Montreal and was an only child.

During the first three months of Marcus's experiment of electron transfer, he read anything he could get his hands on regarding reaction rate theory. He came up with his theory on electron transfer which is also known as Marcus theory. According to his theory, electron transfer is one of the simplest forms of any chemical reaction. Electron transfer can be considered as one of the most basic forms of chemical reaction but without it, life wouldn't exist. so it is really important, it's used in all respiratory functions which include photosynthesis in plants.

Marcus received a Nobel prize for his theory on electron transfer in 1992.

Marcus experiment deals with the building blocks of life and the basic electron transfer, which in fact deals with biology and the natural world.

Melvin Calvin

Born in St.Paul, Minnesota, April 8th 1911. Son of immigrant parents, his father was from Kalvaria, Lithuania. So the Ellis island immigrants named him Calvin. His mother was from Russia Georgia. Soon after his birth they moved to Detroit, Michigan. Calvin then showed interest in science and especially physics and chemistry. In 1927 he got a full scholarship to Michigan college of mining and technology in Houston, where he was the school's first chemistry major. He attended Minnesota university in Minneapolis. He left Minnesota with his doctorate. Calvin used his own savings to supplement a postdoctoral fellowship from the national research council to work for two years with Michael Polany at the university of manchester. His research topic was interactions between quantum mechanical theory and chemical experimentation.

While calvin was in Manchester Joel Hildebrand paid him a visit and invited him to join berkeley faculty, where Calvin would work for the next sixty years.

Calvin's big chance was to come in autumn of 1945; it was known for centuries that the sunlight allows green plants to fix atmospheric carbon dioxide into all organic compounds needed for the plant to grow and reproduce. But people didn't know how it was done. There were theories, but no experimental evidence

The story has it that one day in autumn of 1945 Lawrence and Calvin were walking back to there offices after lunch in the faculty club. Lawrence suggested to Calvin that he might like to use new Carbon 14 to develop it's chemistry and synthesis compounds for medical research, and use it to solve the photosynthesis puzzle. Lawrence would supply the funding and the building, thus the Bio-organic chemistry group was born. As the prime experimental tool, Calvin's group decided to use a green micro-alga rather than the leaves of a better plant.

It eventually became clear that carbon dioxide was converted into hexoses by a reversal of glycolysis the reducing power necessary to drive the process deriving from the capture of sunlight by the energy conversion mechanism of chloroplast.

Calvin himself was later awarded a Nobel prize in chemistry. He himself recognized that he was just one of many scientist who had contributed to this work.

Calvin's work deals with plant's and how they use chloroplast to make themselves green and how they get food, this has to do with chemistry which is a part of biology and our natural world.

Hans Krebs

Born August 25th, 1900, son of George Krebs, an ear, nose and throat surgeon and his wife Alma Davidson. Died November 22nd 1981. He was the elder son and second of three children. As a boy he was impressed by the intact late medieval and renaissance architecture of the old city of Hildesheim, at the edge of which his family lived in a comfortable house. Through the different interest of his father, when they went on there family hikes, his father instilled in him a strong interest in nature in general and in wildflowers imparticular. His father however was skeptical of his intellectual abilities and often made him feel like nothing he did was quite good enough. Hans never made any friends as a child because he was shy and kept to himself. He however was well organized and liked to read. For much of his childhood he kept busy with piano practice. Although his father and mother came from a Jewish background, Hans and his brother Wolf were raised outside the formal faith.

In middle school Krebs ranked first in his class. he did well in all subjects but showed little interest in science, actually His favorite subject was history, which he read. At the age of fifteen, Krebs decided that he wanted to follow his father into medicine. By the late summer of 1918, Hans was old enough to be drafted into the army. Assigned to a signal corps regiment in Hanover, he had completed only a few weeks of basic training when mutinies by sailors at Kiel and elsewhere precipitated the end of the war. Returning home, Krebs was able to obtain an immediate discharge on the grounds that he intended to enroll as a medical student at the University of Göttingen. After completing the summer term, he transferred to the University of Freiburg in order to listen to lectures of its outstanding faculty. Stimulated by accounts of their own scientific discoveries that some of his teachers gave in their lectures, Krebs became interested in trying his hand at research.

After passing with high marks the examination that completed his preclinical training in March 1921, Krebs stayed on for one more semester in Freiburg in order to take in the lectures of the famed pathologist Ludwig Aschoff. During the clinical years in medical school, Krebs was too busy studying and attending lectures and demonstrations to undertake any further research projects.

Krebs went back to Berlin in January 1924 to fulfill his required year of hospital service at the Third Medical Clinic of the University of Berlin. There he carried out preliminary examinations in the outpatient clinic. Encouraged to use his spare time in the laboratory, he undertook on his own a study of the gold sol reaction that was currently in use in some clinical laboratories as a sensitive diagnostic test for syphilis. In collaboration with Annalise Wittgenstein, a member of the clinical staff. he began concurrently experiments on dogs on the passage of foreign substance from the blood into the cerebrospinal fluid, a problem also connected with syphilis, because of difficulties encountered in getting therapeutic drugs such as Salvarsan into the latter fluid to attack the spirochetes lodged in the central nervous system. Drawing on his experience in Möllendorff’s laboratory, Krebs decided to employ dyes whose presence in the cerebrospinal fluid could easily be detected colorimetrically. Wittgenstein proved to be untrained as an investigator, so it fell entirely to Krebs to design the experimental attack and to write the papers reporting their results.

At the University of Freiburg 1932, Krebs discovered a series of chemical reactions by which ammonia is converted to urea in mammalian tissue This cycle also serves as a major source of the amino acid arginine.

Among his many publications is the remarkable survey of energy transformations in living matter, published in 1957, in collaboration with H. L. Kornberg, which discusses the complex chemical processes which provide living organisms with high-energy phosphate by way of what is known as the Krebs or citric acid cycle.

Krebs was elected a Fellow of the Royal Society of London in 1947. In 1954 the Royal Medal of the Royal Society, and in 1958 the Gold Medal of the Netherlands Society for Physics, Medical Science and Surgery were conferred upon him. He was knighted in 1958.