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| 1 | |
A peptide bond is formed between two amino acids by? |
| | A) | A condensation reaction forming an anhydride. |
| | B) | A condensation reaction forming an ester. |
| | C) | A condensation reaction forming an amine. |
| | D) | A condensation reaction forming an amide. |
| | E) | A condensation reaction forming a b-ketoacid. |
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| 2 | |
The majority of amino acids found in proteins are? |
| | A) | a-amino acids. |
| | B) | b-amino acids. |
| | C) | g-amino acids. |
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| 3 | |
In contrast to most amino acids proline is a? |
| | A) | A primary amino acid. |
| | B) | A secondary amino acid. |
| | C) | A tertiary amino acid. |
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| 4 | |
A peptide bond characterizes the structure of proteins while the side chains of the amino acids are responsible for the protein's properties due to? |
| | A) | Their size. |
| | B) | Their shape. |
| | C) | Their electronic properties. |
| | D) | Their ionic properties. |
| | E) | Their hydrogen bonding properties. |
| | F) | All of the above. |
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| 5 | |
At a pH of 7 amino acids are? |
| | A) | Neutral. |
| | B) | Cationic due to the amino group. |
| | C) | Anionic due to the acid group. |
| | D) | Zwitterionic due to both the amino and carboxylic acid groups being charged. |
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| 6 | |
Amino acids are divided in four major groups based on the nature of their side chain. Lys, Arg, and His are? |
| | A) | Amino acids with nonpolar side chains. |
| | B) | Amino acids with polar nonionized side chains. |
| | C) | Amino acids with acidic side chains. |
| | D) | Amino acids with basic side chains. |
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| 7 | |
Amino acids are divided in four major groups based on the nature of their side chain. Asp, Glu, Tyr, and Cys are? |
| | A) | Amino acids with nonpolar side chains. |
| | B) | Amino acids with polar nonionized side chains. |
| | C) | Amino acids with acidic side chains. |
| | D) | Amino acids with basic side chains. |
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| 8 | |
With the exception of Gly all amino acids are chiral. Those found in proteins all have which configuration? |
| | A) | D. |
| | B) | L. |
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| 9 | |
Amino acids are amphoteric and have several pKa values. In order (pKa1, pKa2, pKa3) these values apply to? |
| | A) | The amino group, the side chain, and the acid group. |
| | B) | The acid group, the side chain, and the amino group. |
| | C) | The acid group, the amino group, and the side chain. |
| | D) | The side chain, the amino group, and the acid group. |
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| 10 | |
The isoelectric (or isoionic) point is the pH where the amino acid is? |
| | A) | Positively charged. |
| | B) | Negatively charged. |
| | C) | Neutral. |
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| 11 | |
Electrophoresis separates amino acids based on? |
| | A) | Size. |
| | B) | Shape. |
| | C) | Their ability to form hydrogen bonds. |
| | D) | Their solubility. |
| | E) | Charge. |
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| 12 | |
Which statement about the preparation of amino acids is false ? |
| | A) | They are commonly prepared from acyl halides. |
| | B) | They are commonly prepared from a-halo acids. |
| | C) | They are commonly prepared from an aldehyde via an a-amino nitrile. |
| | D) | They are commonly prepared from diethyl acetoamidomalonate. |
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| 13 | |
Which statement about the reactions of amino acids is false ? |
| | A) | Acylation is common at the amino group. |
| | B) | Esterification is common at the acid group. |
| | C) | Reaction with ninhydrin, at the amino group, produces a colored dye. |
| | D) | They undergo an Aldol condensation. |
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| 14 | |
Which statement about the biological reactions of amino acids is false ? |
| | A) | Reduction amination is used to produce the amino group. |
| | B) | Transamination is used to remove the amino group. |
| | C) | Oxidation is used to add an -OH group. |
| | D) | Decarboxylation is used to removed the carboxylate group. |
| | E) | None of the above. |
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| 15 | |
Which statement about peptides is false ? |
| | A) | Peptides are linear chains of amino acids. |
| | B) | They are only formed from L-amino acids. |
| | C) | The sequence of amino acid residues is written with the amino end to the left, and the carboxylate end to the right. |
| | D) | The peptide bond has a planar geometry. |
| | E) | The two a-carbon atoms on either side of the peptide bond are anti to each other. |
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| 16 | |
The sequencing of a peptide can involve any of the following steps except? |
| | A) | Hydrolysis of the peptide. |
| | B) | Partial hydrolysis by proteases. |
| | C) | Using Sanger's reagent to identify N-terminal amino acids. |
| | D) | Identify the C-terminal amino acid by using a carboxypeptidase. |
| | E) | The use of paper chromatography to separate amino acids. |
| | F) | Use Edman degradation to analyze the peptide. |
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| 17 | |
Which statement about the synthesis of peptides is false ? |
| | A) | The reactions can only be carried out in solution. |
| | B) | Both the N-terminal amino group, and the C-terminal carboxylate group must be protected. |
| | C) | For peptide bond formation to occur the free carboxylate group must be activated. |
| | D) | Once the new peptide bond has been formed the protecting groups must be removed. |
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| 18 | |
The primary structure of a protein refers to? |
| | A) | The sequence of amino acids. |
| | B) | The conformation of short segments of amino acids, i.e. an a-helix and a b-sheet. |
| | C) | The conformation of the entire peptide chain. |
| | D) | The association between proteins. |
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| 19 | |
The secondary structure of a protein may contain an a-helix and a b-sheet. The difference between them is the location of the hydrogen bonds. In an a-helix the hydrogen bonds are? |
| | A) | Between amino acids on two adjacent chains. |
| | B) | Between amino acids within a single chain. |
| | C) | Between amino acids on two different proteins. |
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| 20 | |
The tertiary structure of a protein is affect by all of the following except? |
| | A) | The primary structure. |
| | B) | The secondary structure. |
| | C) | Disulfide links. |
| | D) | The presence of metal ions. |
| | E) | The environment it is in, i.e. the solvent. |
| | F) | The quaternary structure. |
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| 21 | |
Cofactors, or coenzymes, primarily aid in which of the following reactions? |
| | A) | Proton donation. |
| | B) | Proton abstraction. |
| | C) | Oxidation / reduction. |
| | D) | Nucleophilic addition to carbonyl groups. |
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