Lecture 1

Lecture 1 - Chemistry of biological systems: Bio-organic...

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Chemistry of biological systems: Bio-organic elements are only a few C, H, O, N, P, S Trace elements Organic chemistry: Originally molecules of natural origin; now usually meaning molecules containing C Valence C = 4; N = 3; O = 2; H = 1 Reactive groups Hydroxyl, amino, carboxyl, carbonyl, aldehyde, ketone, carboxyl, phosphoryl Trace elements are required by an organism but only in minute quantities. Many trace elements, like iron (Fe), are required by all organisms. For example, a daily intake of 0.15 milligrams of iodine is required for normal activity of the human thyroid gland. A reduction from this level can cause goiter, an abnormal growth of the thyroid. Other trace elements are required only by some species Most deficiency diseases don’t have clear-cut symptoms - A methane molecule (CH 4 ) has all four hybrid orbitals shared and has hydrogen nuclei at the corners of the tetrahedron (hydrocarbon) - ELECTRONEGATIVITY: ability of an atom to attract electrons (attracting more = more e -) o Strongly electronegative atoms attempt to pull the shared electrons toward themselves (H – O, C – C, O – O) - POLARITY: difference in electronegativity o Equal Electronegativity: nonpolar (H 2 , methane) o Unequal Electronegativity: polar (H 2 O) Weak chemical bonds are important - Within a cell, weak, brief bonds between molecules are important to a variety of
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This note was uploaded on 11/18/2011 for the course BISC 220L taught by Professor Herrera,mcclure during the Spring '07 term at USC.

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Lecture 1 - Chemistry of biological systems: Bio-organic...

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