Chapter 5 Review Quizzes

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. Which of the following amino acids are aromatic?

Phenylalanine, alanine, and glycine correct incorrect

Phenylalanine, histidine, and tyrosine correct incorrect

Histidine, tyrosine, and tryptophan correct incorrect

Tyrosine, tryptophan, and cysteine correct incorrect

Phenylalanine, tyrosine, and tryptophan correct incorrect

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

Prevent hydrolysis correct incorrect

Decrease solubility of protein molecules correct incorrect

Maintain disulfide linkages correct incorrect

Promote repulsion by protein molecules having like charges correct incorrect

Increase hydration of acid and amine groups correct incorrect

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. 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:

α-alanine correct incorrect

β-alanine correct incorrect

γ-alanine correct incorrect

Delta alanine correct incorrect

Epsilon alanine correct incorrect

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. The major function of heat shock protein is:

To maintain glutathione in reduced form at high temperatures correct incorrect

To cleave glutathione at the disulfide bond correct incorrect

To promote dehydration of normal proteins correct incorrect

To hydrolyze toxic proteins correct incorrect

To help correctly refold damaged proteins correct incorrect

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. Which of the amino acids is optically inactive?

Alanine correct incorrect

Glutamic acid correct incorrect

Leucine correct incorrect

Glycine correct incorrect

Cysteine correct incorrect

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. 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?

Tryptophan correct incorrect

Glycine correct incorrect

γ-aminobutyric acid (GABA) correct incorrect

Cystine correct incorrect

Glutamic acid correct incorrect

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. 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:

More soluble in water correct incorrect

Less soluble in water correct incorrect

Soluble only in acids correct incorrect

Soluble only in nonpolar solvents correct incorrect

Soluble as long as the temperature is kept low correct incorrect

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. The zwitterion form of valine:

Is the form which exists in a solution near a pH of 7.0 correct incorrect

Is the form which has no charges whatsoever correct incorrect

Is the form present in acidic solution correct incorrect

Is the form you=d find in basic solutions correct incorrect

Has a charge of -1 correct incorrect

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. 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:

At its amine group correct incorrect

At the -COOH group having the highest pK correct incorrect

At the -COOH group having the lowest pK correct incorrect

At both the -COOH groups at the same time correct incorrect

At both of the amine and -COOH groups closest to each other correct incorrect

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

2.18 correct incorrect

8.95 correct incorrect

10.79 correct incorrect

5.56 correct incorrect

9.87 correct incorrect

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. 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?

The heat may discolor the protein correct incorrect

The heat may cause protein molecules to stick together correct incorrect

Heat causes discomfort correct incorrect

Increased temperature results in increased molecular vibration, decreasing intramolecular bonding correct incorrect

Increased temperature increases entropy correct incorrect

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

Methionine correct incorrect

Lysine correct incorrect

Cysteine correct incorrect

Aspartic acid correct incorrect

None. Amino acids are tasteless. correct incorrect

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

Acids and bases correct incorrect

Cysteine and cysteine correct incorrect

Lysine and glycine correct incorrect

Glycine and phenylalanine correct incorrect

Amine and acid groups correct incorrect

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. 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?

ALA - LEU - THR - GLY - PHE - VAL - SER - ILE correct incorrect

ALA - PHE - GLY - THR - VAL - CYS - LEU - SER correct incorrect

ALA - VAL - GLY - THR - PHE - CYS - LEU - SER correct incorrect

VAL - SER - THR - GLY - ALA - LEU - PHE - CYS correct incorrect

VAL - SER - ALA - LEU - THR - GLY - PHE - CYS correct incorrect

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. 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:

Hemoglobin will absorb oxygen best in acidic solutions correct incorrect

Hemoglobin will absorb oxygen readily in lungs and release oxygen readily in working muscle correct incorrect

Hemoglobin will release oxygen readily in lungs and absorb oxygen readily in working muscle correct incorrect

Hemoglobin will take up oxygen best when there is very little available correct incorrect

Under very acidic conditions in lungs, hemoglobin will release oxygen correct incorrect

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. 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:

Toward the positive electrode correct incorrect

Toward the negative electrode correct incorrect

Toward the neutral electrode correct incorrect

In the same direction as the basic amino acid correct incorrect

Not at all correct incorrect

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. 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:

Shortages of lead for musket balls correct incorrect

Poisoning due to the fact that heavy metal salts precipitate protein irreversibly correct incorrect

Dementia caused by the excessively sweet character of the local wines correct incorrect

Choking due to the lack of solubility of pastas correct incorrect

Shortages of catgut needed for violin strings, resulting in dementia of leaders such as Nero correct incorrect

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

Rise correct incorrect

Fall correct incorrect

Remain the same correct incorrect

Be unaffected unless alcohol were added correct incorrect

Be unaffected unless a reducing agent were added correct incorrect

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

Taste sour correct incorrect

Contain in its structure more basic groups than acidic groups correct incorrect

Contain sulfhydryl groups in its structure correct incorrect

Contain more acidic functional groups than basic groups in its structure correct incorrect

Contain at least one aromatic ring correct incorrect

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

Amino acids contain acid functional groups correct incorrect

Amino acids contain basic functional groups correct incorrect

Amino acids are hydrophobic correct incorrect

Amino acids are amphoteric correct incorrect

Amino acids are found in every living thing correct incorrect

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

Amyloid deposits correct incorrect

Calcification correct incorrect

Atherosclerosis correct incorrect

Hydroxyapatite correct incorrect

Protein bundling correct incorrect

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. 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?

Sulfur correct incorrect

Sulfur bonded to another sulfur atom correct incorrect

An extra carboxylic acid group correct incorrect

An extra amine group correct incorrect

Phosphorus correct incorrect

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

Quaternary correct incorrect

Primary correct incorrect

Tertiary correct incorrect

Secondary correct incorrect

Nonpolar correct incorrect