Modern Biology: Chapter 3 Biochemistry

Carbon Compounds Organic compounds – primarily Carbon atoms Large, complex molecules essential for life Contributes to diversity of life Carbon bonding Has 4 valence electrons Can form single, double, or triple covalent bonds Can form straight or branched chains of itself Can form rings of itself

Functional Groups Influence characteristics of molecules Make polar with addition of charged entities Affect chemical reactions molecules undergo Allow bond formation between molecules Some of these groups are – Hydroxyl (R-OH) Carboxyl (R-COOH) Phosphate (R-PO4) Amine (R-NH2)

Large Carbon Molecules Monomers Small, simple molecules Amino acid, fatty acid, nucleotide, monosaccharide Polymer Monomers join via condensation reactions Polypeptides Disaccharides Polymers break down with hydrolysis reaction Macromolecules -- Formed from large polymers -- Protein, lipids, nucleic acids, carbohydrates

Energy Currency Compounds store energy in chemical bonds Certain ones’ overall structure stores energy ATP (Adenosine triphosphate) NADH (Nicotinamide adenine dinucleotide) NADPH (Nicotinamide adenine dinucleotide phosphate) FADH2 (Flavin adenine dinucleotide)

Molecules of Life Carbohydrates Proteins (CH2O)n general formula n = 3–8 monosaccharides Hundreds of glucose monomers make glycogen (animals) or starch & cellulose (plants) Proteins Composed of amino acids (C, H, O, N et al) 20 essential amino acids, differ in –R groups Amino acids joined via peptide bond between amino side of 1 & carboxyl side of another Enzymes are protein catalysts

Molecules of Life, continued Lipids Large, nonpolar organic molecules Higher ratio of C & H atoms to O atoms than sugar Types Fatty acids (12-28 C chain with –COOH group) Triglycerides (3 fatty acids attach to glycerol) Phospholipids (2 fatty acids attach to phosphate on glycerol’s 3rd carbon) Waxes (long fatty acid attaches to long alcohol chain) Steroids (Four fused carbon rings + functional groups)

Molecules of Life, continued Nucleic acids Store and transmit important info in the cell DNA: determines traits & directs cell activities RNA: stores/transmits info from DNA Composed of nucleotides Adenine, guanine, cytosine, thymine or uracil Made of 3 compartments Phosphate group 5-C sugar [(deoxy)ribose] Ring-shaped nitrogenous base