QUIZ 1. What is the amino acid cutoff, above which a polypeptide becomes a protein? a. 10 b. 20 c. 50 d. 100 Answer: c. A protein is a polypeptide that will be at least fifty amino acids in total length. 2. What is considered the simplest amino acid? a. Glycine b. Lysine c. Isoleucine d. Alanine Answer: a. Glycine is the simplest amino acid, consisting only of NH2CH2COOH, which serves to have the most basic definition of an amino acid, having an amino group and a carboxylic acid side chain. 3. What type of amino acid makes up the twenty amino acids seen in proteins? a. All alpha amino acids b. All beta amino acids c. All gamma amino acids d. A mixture of alpha and beta amino acids Answer: a. All amino acids seen in nature are consisted of alpha amino acids, which means that the amino group is attached to the alpha carbon or the carbon just adjacent to the carboxylic acid carbon. It means that the NH2 side chain becomes NH3+ and the COOH side chain becomes COO-.
216
