Chest pain is always an alarming symptom since it usually raises the fear of heart disease. And because chest pain may indeed be a sign of angina or of some other heart problem, it is always a good idea to have it checked out. But heart disease is only one of the many types of conditions that can produce chest pain.
Concept 27 Mutations are changes in genetic information. Hermann Muller received the 1946 Nobel Prize in Physiology or Medicine for his work on mutations induced by X-rays. Seymour Benzer used genetics to prove that mutations were caused by changes in the DNA sequence.
Rutherford's Planetary Model of the Atom By 1911 the components of the atom had been discovered. The atom consisted of subatomic particles called protons and electrons. However, it was not clear how these protons and electrons were arranged within the atom. J.J. Thomson suggested theplum pudding model. In this model the electrons and protons are uniformly mixed throughout the atom: Rutherford tested Thomson's hypothesis by devising his gold foil experiment.