The chemistry of life: cell chemistry is carbon chemistry, c forms the backbone of essentially all molecules of importance to the cell, valence = 4. C forms stable bonds: bond energy of c single covalent bonds is. Linear, branched or cyclic c chains: note common presence of o, n, p, s. Functional groups: cellular ph is above 7, cell chemistry is water based, h2o typically composes 75-85% of cell by weight, polarity and the formation of hydrogen bonds. Bond energy = 1 4 kcal/mol: properties as solvent. Introduction to macromolecules: carbohydrates, polymers of monosaccharide"s (polysaccharides) Structural: when you run out of glycogen you begin to fatigue, chitin is a key constituent of the exoskeleton of lobsters etc. and insects, monosaccharides, cnh2non n = 3 to 7. A nucleic acid is polymer (a string of nucleotides), and a nucleotide is the monomer. Nucleoside= ex// ribose sugar plus adenine (called nucleoside adenosine)