Question 1

Which of the following correctly represents the peptide bond formation between alanine (Ala) and glycine (Gly) during the synthesis of the tripeptide Ala-Gly-Val?

Accepted Answer

A condensation reaction occurs, releasing $$\mathrm{H_2O}$$ and forming a bond between the carboxyl group of Ala and the amino group of Gly.

Question 2

Which amino acid in the provided structures contains a secondary amine in its backbone?

Accepted Answer

Proline

Question 3

In the Fischer projection of D-glucose, which carbon is the anomeric carbon after cyclization to the pyranose form?

Accepted Answer

C1

Question 4

Which of the following best describes the mechanism of acetal formation from a hemiacetal and an alcohol under acidic conditions?

Accepted Answer

The hemiacetal oxygen is protonated, water leaves, and the alcohol attacks the resulting carbocation.

Question 5

Which of the following statements about epimerization is correct?

Accepted Answer

Epimerization involves the inversion of configuration at a single stereocenter in a sugar molecule.

Question 6

During the oxidation of a monosaccharide, which functional group is typically converted to a carboxylic acid?

Accepted Answer

The aldehyde group ($$\mathrm{-CHO})$$

Question 7

Which of the following best explains why glycine is unique among the standard amino acids?

Accepted Answer

It does not have a chiral center.

Question 8

In the context of peptide synthesis, why is protection of functional groups necessary?

Accepted Answer

To prevent unwanted side reactions at reactive sites during coupling steps.

Question 9

Which of the following is the correct Haworth projection for the cyclic form of D-glucose?

Accepted Answer

A six-membered ring with the anomeric OH group down for $$\alpha-D-$$glucose and up for $$\beta-D-$$glucose.

Question 10

Which reaction is responsible for the equilibrium between the ring and linear forms of glucose in aqueous solution?

Accepted Answer

Hemiacetal formation and hydrolysis

Question 11

Which of the following best describes the difference between Fischer and Haworth projections?

Accepted Answer

Fischer projections show the linear form, while Haworth projections show the cyclic form of sugars.

Question 12

Which amino acid from the structures provided is aromatic and nonpolar?

Accepted Answer

Phenylalanine

Question 13

Which of the following is a correct statement about the oxidation of glucose?

Accepted Answer

Oxidation of the aldehyde group at C1 yields gluconic acid.

Question 14

Which of the following best describes the product when D-glucose undergoes reduction?

Accepted Answer

D-glucitol (sorbitol)

Question 15

Which of the following is a correct description of the mechanism for the formation of a glycosidic bond?

Accepted Answer

The anomeric hydroxyl group reacts with an alcohol, releasing water and forming an acetal linkage.

Question 16

Which of the following best explains why acetals are stable in neutral and basic solutions but not in acidic solutions?

Accepted Answer

Acetals are hydrolyzed in acid due to protonation of the oxygen, making them good leaving groups.

Question 17

Which of the following is a correct statement about the synthesis of peptides in the laboratory?

Accepted Answer

Peptide synthesis requires activation of the carboxyl group, often using reagents like DCC (dicyclohexylcarbodiimide).

Amino Acids, Peptide Synthesis, and Carbohydrate Mechanisms: Mini-Study Guide

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