The four nitrogenous bases that make up the DNA structure are divided into two groups, called purines and pyrimidines. Adenine and guanine are purines, and chemically are double-ringed structures - a five cornered ring and a six cornered ring. They are much larger than pyrimidines.
James Mason (I) (1909â1984) James Mason was a great English actor of British and American films. He was born in Yorkshire, and attended Marlborough and Cambridge, where he discovered acting on a lark, and abandoned a planned career as an architect. Following work in stock companies, he joined the Old Vic under the guidance of Sir Tyrone Guthrie and of Alexander Korda, who ...
James Pierson Beckwourth, born James Beckwith and generally known as, Jim Beckwourth (April 26, 1798 or 1800 â October 29, 1866 or 1867) was an American mountain man, fur trader, and explorer. A mulatto born into slavery in Virginia, he was freed by his father (and master) and apprenticed to a blacksmith; later he moved to the American West.