The Chemistry of Molecular Biology Mary O’Brien September 23, 2003

Chemical Structures of Cells Proteins –Amino Acids Nucleic Acids –Nucleotides Polysaccharides –Monosaccharides

The Basics of Amino Acids 20 amino acids All amino acids in nature are L form Structure consists of C , to which an amino group, a carboxyl group, a hydrogen atom, and a variable group Amino acids are classed according to their R group

From Amino Acids to Protein peptide bond isoleucinylphenylalanylalanine ILE-PHE-ALA

The Structure of Nucleotides Common structure of phosphate group, base, five-carbon sugar Sugar is either DNA or RNA Bases are adenine, guanine, cytosine, thymine (DNA), uracil (RNA) sugar base phosphate group

Nucleotides Build Nucleic Acids 1’ carbon atom of sugar attaches to nitrogen of purine or pyrimidine Acidic nature due to phosphate group Nucleotides are linked by phosphodiester bonds

The Simplicity of Monosaccharides Carbohydrates of combinations of carbon and water in a one-to-one ratio Except for fructose, all sugars are in nature are D form D-Glucose (C 6 H 12 O 6 ) is primary energy source

The Complexity of Polysaccharides Disaccharides are simplest polysaccharides Anomeric carbon of one sugar molecule is linked to hydroxyl oxygen of another sugar molecule Polysaccharides can contain dozens to hundreds of monosaccharides

Biological Macromolecules Multiple small molecules are covalently linked to form polymers Amino acids make proteins, nucleotides form nucleic acids, and polysaccharides are made of monosaccharides