Post on 22-Dec-2015
The Chemistry of Molecular The Chemistry of Molecular BiologyBiology
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 Proteinpeptide bond peptide bond
isoleucinylphenylalanylalanineILE-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
phosphategroup
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 (C6H12O6) 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