500
A description of stuctural features you would look for to determine whether a given molecule was a carb, lipid, nucleic acid, or amino acid.
Carb: The atoms are some multiple of CH20 (for example, C6H12O6. Don't forget to count hydrogens that are not drawn)
Lipid: hydrophobic. Large areas of only carbons and hydrogens.
Nucleic acid: phosphate group(s), sugar (ribose or deoxyribose), nitrogenous base (A, C, T, G, U)
Amino acid (single): a central carbon that is bonded to a COOH, an NH2 or NH3, and a variable R group
Amino acid (in a polypeptide): instead of an NH2 and COOH, look for a carbon double bonded to an O and single bonded to an N. This is the peptide bond.