Environmental Biology for Engineers and Scientists D.A. Vaccari, P.F. Strom, and J.E. Alleman © John Wiley & Sons, 2005 Chapter 3 – The Substances of Life

Figure 3-1. Structures of several small, biologically important organic molecules.

Figure 3-2. Electronegativity of biologically important elements. This shows the portion of the periodic table containing many of the elements that are important to life. The numbers indicate the electronegativity of the corresponding elements. (From Pauling, Linus, 1960)

Figure 3-3. Fraction of undissociated acid for acetic acid (pKa = 4.5). Points shown are for pH 3.5, 4.5, and 5.5.

Figure 3-4. Tetrahedral structure of carbon bonding, and a methane molecule. (Based on Gaudy) H H C H H

Figure 3 ‑ 5. Three-dimensional view of glyceraldehyde structure. (a) Mirror-image views; (b) views showing orientation with hydrogen of central carbon pointed towards viewer.

Monosaccharide structures

Ring structures of glucose and fructose.

A common disaccharide

Figure 3 ‑ 6. Polymers of glucose: (a) starch or glycogen showing maltose repeating disaccharide unit; (b) cellulose with cellobiose repeating unit.

Figure 3 ‑ 7. Structures of some of the more common fatty acids. Basic structure: R-COOH Saturated fatty acids: FormicHCOOH AceticCH 3 COOH ProprionicCH 3 CH 2 COOH n-ButyricCH 3 (CH 2 ) 2 COOH CaproicCH 3 (CH 2 ) 4 COOH PalmiticCH 3 (CH 2 ) 14 COOH StearicCH 3 (CH 2 ) 16 COOH Unsaturated fatty acids OleicCH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COOH LinoleicCH 3 (CH 2 ) 4 CH=CHCH 2 CH=CH(CH 2 ) 7 COOH ArachidonicCH 3 (CH 2 ) 4 -(CH=CH-CH 2 ) 4 -(CH 2 ) 2 -COOH

Figure 3 ‑ 8. Formation of triglyceride from glycerol and fatty acids.

Phospholipid structure.

Figure 3-9. Surfactant structures formed in solution.

Steroid structure, example of cholesterol. Structure of poly-β-hydroxybutyric acid. The repeating unit is outlined.

Peptide bond formation. Amino acid structure

Figure Tertiary and quarternary protein structure as shown in bovine insulin. This protein consists of two polypeptide chains joined by two disulfide bonds. Another disulfide bond within the smaller chain contributes to the molecule’s shape.

Figure Enzyme control of proximity and orientation of substrates.

Figure A hypothetical enzyme mechanism involving a cofactor. + + Enzyme Cofactor Substrate + Enzyme- substrate- cofactor complex

Figure Nucleotide structure.

Figure DNA molecule section showing phosphate-sugar “backbone”.

Asp Asn Gly Ser Thr Glu Lys His Gln Ala Tyr Pro Arg Val Ile CySSCy Leu Phe Trp Met Figure Schematic of a two-dimensional thin layer chromatograph separation of amino acids. [Based on White, et. al., 1973.]