Swiss biochemist Johann Friedrich Miescher (1844-95) was one of the first scientists intent on identifying the hereditary material in nuclei. In order to isolate nuclei with minimal contamination, Miescher chose to work with cells that have large nuclei and very little cytoplasm. At first he chose white blood cells extracted from the pus in used bandages from a hospital; later, he used the sperm of salmon—probably more agreeable to work with than used bandages! Miescher isolated an acidic substance rich in phosphorus, which he named nuclein. His student, Richard Altmann, later called it nucleic acid—a term we now use for both DNA and RNA. Miescher correctly guessed that "nuclein" (DNA) was the hereditary matter of the cell, but he was unable to provide strong evidence for this conjecture, and his work was harshly criticized. He died of tuberculosis at the age of 51.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.