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Unformatted text preview: Biological Chemistry The universe is composed of energy and matter. Life, the Universe, and Everything Matter is in the form of chemicals. • Chemicals are constructed from atoms. • Different types of matter, i.e., different elements, have different atoms. The Atom • A single unit of matter • Composed of three types of subatomic particles – Neutrons (no): mass = 1 atomic mass unit no electrical charge (neutral) – Protons (p+): mass = 1 atomic mass unit positive electrical charge (+1) – Electrons (e–): mass is trivial negative electrical charge (–1) Atomic Number • A chemical reaction is the interaction of electrons from different atoms. • The number, distribution and activity of electrons around an atom’s nucleus is determined by the number of protons in that nucleus. • At the beginning of the universe, energy was converted 2 into matter. Big Bang! • Only in rare circumstances, like inside stars and atomic blasts, matter is converted back into energy. m E= c •Energy is often converted from one form into another: (e.g., light energy into chemical energy; chemical enegy into kinetic energy; kinetic energy into heat energy; etc.) but it is neither created nor destroyed. •But matter, with rare exceptions, stays the same type of matter. Atomic Structure • Neutrons and protons form the nucleus • Atomic Mass (Atomic Weight) = number of protons and neutrons combined • Electrons orbit around the nucleus [p+] [n °] [e-] Partial Periodic Table atomic number • .. The “chemical identity” (type of element) for any atom is determined by the number of protons in its nucleus! # of p+ = the Atomic Number for that atom. E.g.: Any atom that has 6 p + in its nucleus (atomic number = 6) is defined as carbon , no matter how many e - or n ° it has! Heyer 1 Biological Chemistry Isotopes 96% of body mass is composed of four different elements Table 2.1 • Oxygen (65%) • Carbon (18%) • Hydrogen (10%) • Atoms of the same element (i.e., same atomic number) but with differing numbers of neutrons, ha...
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This note was uploaded on 09/02/2011 for the course BIOL 6B taught by Professor Heyer during the Spring '10 term at DeAnza College.

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