Amino acids, amides + chirality

• What are the two functional groups of amino acids?

  NH2 and COOH (amine and carboxylic acid)

  
• What is the general formula for α-amino acids?

  1. CH(NH2)-COOH

  
• Are α-amino acids chiral? Why?

  Yes, one carbon has 4 different substituents, except glycine.
• What is a zwitterion?

  It is an ion with both a permanent positive and negative charge, but is neutral overall.
• How do zwitterions occur in amino acids?

  COOH is deprotonated to COO^- and NH2 is protonated to NH3⁺.
• What happens to amino acids in acidic conditions?

  Amino acids gain a proton on the NH2 group.
• What happens to amino acids in alkaline conditions?

  Amino acids lose a proton from the COOH group.
• What is the peptide linkage?

  • CONH-

  
• What are the structures of primary and secondary amides?

  Primary amides have one carbon attached to the nitrogen, while secondary amides have two.

  
• What property must a carbon atom have for the molecule to display optical isomerism?

  It must have 4 different substituents attached to it.
• What are the similarities and differences between two optical isomers?

  They have the same atoms and bonds but are non-superimposable mirror images.
• What word is used to describe optically active molecules?

  Chiral
• Give two examples of chiral molecules.

  All alpha amino acids except glycine and lactic acid.
• Draw one of the enantiomers of lactic acid.

  Enantiomers of lactic acid are mirror images of each other.