Transcript The Chemistry of Molecular Biology

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 Ca,
to which an amino
group, a carboxyl group,
a hydrogen atom, and a
• Amino acids are classed
variable group
according to their R group
From Amino Acids to Protein
peptide bond
isoleucinylphenylalanylalanine
ILE-PHE-ALA
peptide bond
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)
base
phosphate
group
sugar
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