LEHNINGER BIOCHEMISTRY CHAPTER 3 QUESTIONS WITH CORRECT ANSWERS

The chirality of an amino acid results from the fact that its α carbon: A) has no net charge. B) is a carboxylic acid. C) is bonded to four different chemical groups. D) is in the L absolute configuration in naturally occurring proteins. E) is symmetric. CORRECT ANSWER C) is bonded to four different chemical groups. Of the 20 standard amino acids, only ___________ is not optically active. The reason is that its side chain ___________. A) alanine; is a simple methyl group B) glycine; is a hydrogen atom C) glycine; is unbranched D) lysine; contains only nitrogen E) proline; forms a covalent bond with the amino group CORRECT ANSWER B) glycine; is a hydrogen atom Two amino acids of the standard 20 contain sulfur atoms. They are: A) cysteine and serine. B) cysteine and threonine. C) methionine and cysteine D) methionine and serine E) threonine and serine. CORRECT ANSWER C) methionine and cysteine All of the amino acids that are found in proteins, except for proline, contain a(n): A) amino group.