Chemical Basis of Life F10

Chemical Basis of Life F10 - 3Biol 121 Anatomy and...

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3Biol 121 Anatomy and Physiology I Chemical Basis of Life I. Matter and Energy A. Matter - anything that occupies space and has mass. For all practical purposes we can consider mass to be the same as weight (except weight varies with gravity and mass does not). Exists in three states: solid, liquid and gaseous states. Examples of each are found in the human body. B. Energy - The capacity to do work or put matter into motion. Has no mass does not take up space. Measured only by its effects on matter. With few exceptions energy can easily be converted from one form to another. Ex: chemical energy of food is converted mechanical energy of muscle contraction. Energy conversions are inefficient and some is lost as heat. This heat makes us warm blooded animals and contributes to our relatively high body temperatures. C. Composition of Matter 1. Elements - substances that cannot be broken down into simpler substances by ordinary means. Molecules are formed by identical atoms. Ex: oxygen, carbon, gold, iron. Four elements - carbon, oxygen, hydrogen and nitrogen make up about 96% of the body. Each element is designated by a one or two letter atomic symbol (usually the first letters of the elements name). Carbon = C, Oxygen = 0, Calcium = Ca, Hydrogen = H, Sodium = Na, Chloride = Cl. 2. Atoms - the building blocks of elements. Each elements atoms differ from those of all other elements and give the element its unique physical and chemical properties. Atoms are clusters of even smaller particles called protons (+ charge), neutrons (neutral) and electrons(- charge). Nucleus contains equal number of protons and neutrons. The nucleus is surrounded by orbiting electrons equal in number to the protons. All atoms are electrically neutral. Orbital - regions around the nucleus in which the electrons circle the nucleus.
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Hydrogen has a single electron. Carbon has 6 Oxygen has 8 Sodium has 11 Chloride has 17 3. Molecule - combination of two or more atoms held together by chemical bonds. The atoms are identical. Oxygen or O2. 4. Compound - when two or more different kinds of atoms bind together. Ex: Water 5. Isotopes - have the same number of protons and electrons but vary in the number of neutrons they contain. Ex: tritium - isotope of hydrogen that has one proton and two neutrons. 6. Radioisotopes - unstable isotopes that spontaneously decompose into more stable forms. This process results in detectable emissions. This radioactivity can be detected with scanners and therefore radioisotopes are valuable tools for biological research and medicine. EX: to localized damaged or cancerous tissue. Iodine 131 used to determine the sizes and activity of the thyroid gland D. Types of Chemical Bonds 1. Ionic Bonds Electrons can be transferred from one atom to another. The atom that gains one or more electrons acquires a negative charge and is called
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This note was uploaded on 02/02/2011 for the course BIOL 121 taught by Professor Hopper during the Fall '10 term at University of Evansville.

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Chemical Basis of Life F10 - 3Biol 121 Anatomy and...

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