November 22 in Science History – Hans Adolf Krebs and the Citric Acid Cycle

Hans Adolf Krebs
Hans Adolf Krebs (1900 – 1981) Nobel Foundation

November 22 marks the passing of Hans Adolf Krebs. Krebs was a German chemist who was awarded the 1953 Nobel Prize in Medicine for the discovery of the citric acid cycle or the Krebs cycle.

The Krebs cycle is a series of chemical reactions that take place in cells where food is broken down into carbon dioxide, water, and energy. The reactions take place in the mitochondria of cells as part of the process of cellular respiration. At the beginning of the cycle, an acetyl group broken down from food and combines with a four-carbon molecule called oxaloacetate to make a six-carbon compound, citric acid. The citric acid molecule is rearranged and stripped of two of its carbon atoms during the process releasing carbon dioxide and 4 electrons. At the end of the cycle, a molecule of oxaloacetate remains, which can combine with another acetyl group to being the cycle again.

Notable Science History Events for November 22

1981 – Hans Adolf Krebs died.

1917 – Andrew Fielding Huxley was born.

Andrew Huxley was born. Huxley is the English physiologist who shares the 1963 Nobel Prize in Medicine with John Carew Eccles and Alan Hodgkin for their discoveries and research involving nerve cells. Huxley and Hodgkin’s research involved nerve action potentials. These are the electrical signals that enable a nerve’s coordination with the central nervous system. They hypothesized the existence of ion channels that transport the actual nerve signal that would be discovered in the 1970s.

1907 – Asaph Hall III died.

Asaph Hall (1829 - 1907) US Navy. On November 22 in science history, the discoverer of Mars' moons died.
Asaph Hall (1829 – 1907) US Navy. On November 22 in science history, the discoverer of Mars’ moon died.

Hall was an American astronomer who discovered the two moons of Mars, Phobos, and Deimos. He worked for the US Naval Observatory where he was responsible for operating the world’s largest refracting telescope of the time.

During his tenure, he determined the orbits of several planet’s satellites and the rotation rate of Saturn.

1904 – Louis-Eugène-Félix Néel was born.

Louis Néel
Louis Néel (1904 – 2000)

Néel was a French physicist who was awarded half the 1970 Nobel Prize in Physics for his discoveries concerning ferromagnetism and antiferromagnetism and contributions to solid state physics. He researched magnetism on the molecular level and found the electrons in ferromagnetic materials tend to spin in all the same directions. In non-magnetic material, side by side electrons will spin in opposite directions and cancel each other’s magnetic field out. He called this property antiferromagnetism.