Chapter 5 Review Quiz

Amino Acids, Peptides, and Proteins

. Which of the following amino acids are aromatic?

. To precipitate proteins from solution, technicians often adjust the pH to the isoelectric point of the protein. The purpose in doing this is to:

. Alanine contains three carbons, and the amine group is usually found on the second carbon. Another form of alanine, found in nervous tissue, has an amine group on the number 3 carbon. The correct name for this form of alanine is:

. The major function of heat shock protein is:

. Which of the amino acids is optically inactive?

. γ-Hydroxybutyric acid, the so-called Adate rape@ drug, probably owes its effects to the fact that it is similar in structure to another amino acid which functions as a neurotransmitter which decreases anxiety. Which one?

. The zwitterion of isoleucine does not readily dissolve in water. If treated with NaOH, isoleucine reacts, forming a salt. This should make the treated isoleucine:

. The zwitterion form of valine:

. Treatment of one mole of glutamic acid with a mole of sodium hydroxide forms monosodium glutamate, a meat tenderizer sometimes known as MSG. If you added one mole of glutamic acid to one mole of sodium hydroxide, the glutamic acid would react first:

. The pK=s of lysine are 2.18. 8.95, and 10.79. The correct isoelectric point of lysine is:

. Heat is extremely hazardous to proteins. Even minor changes in temperature may result in decreased enzyme activity. If the heat is not high enough to denature the protein, how could it decrease activity?

. Glycine tastes sweet. Which of the following amino acids would you expect to taste sour?

. During the process of getting a "permanent" wave of one's hair, bonds are broken and formed by mild oxidation and reduction between:

. One of the fundamental pieces of information concerning a protein is the primary structure, or sequence of amino acids. In the old days, a researcher would cut a large protein into fragments and assign each fragment, typically ten or so amino acids long, to a graduate student for analysis. If you were a graduate student faced with such a challenge, you might subject some of your white powder sample to acid hydrolysis and find that the following amino acids were present:
ALA PHE GLY THR VAL CYS LEU SER
Suppose that treatment of the intact peptide with the enzyme aminopeptidase released valine. Treatment of the original peptide with the enzyme carboxypeptidase released cysteine. Partial hydrolysis produced the following fragments:
ALA-LEU THR-GLY VAL-SER PHE-CYS SER-ALA GLY-PHE LEU-THR
Which of the following is the correct structure for the original peptide?

. The Bohr effect describes the cooperative binding of oxygen by hemoglobin. At low oxygen concentrations, hemoglobin binds oxygen poorly, but at high oxygen concentrations, oxygen is readily taken up by hemoglobin. In addition, oxygen is bound readily at high pH and released readily at low pH. Using this model, you could predict that:

. If a mixture of an acidic, a basic, and a neutral amino acid are placed on an electrophoresis gel or strip at a pH of 7.0, the acidic amino acid will move:

. Ancient Romans were reputed to have used an artificial non-caloric sweetener known as sapa. While the identity of this substance is not known with certainty, it may have actually been lead carbonate, a sweet-tasting compound. Extensive use of this sweetener would probably have lead to:

. If a pentapeptide made up of alanine, phenylalanine, tyrosine, lysine, and valine were added to water, the pH of the solution would probably:

. For an amino acid to be classified as basic, it must:

. Which of the following characteristics of amino acids allows them to form zwitterions?

. Alzheimer's disease is a debilitating condition characterized by loss of memory, disorientation, and accumulation in the brain of tangles of protein called:

. Most amino acids contain hydrogen, oxygen, carbon, and nitrogen arranged in several typical configurations. Which of the following is least likely to be found in an amino acid?

. Hemoglobin contains two alpha chains of protein and two beta chains. The maximum degree of protein structure shown by hemoglobin is:

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