Q: Which of the following is an example of a constitutional isomer?

$$\mathrm{H_3C-CH_2$-OH}$$ \text{ and } $$\mathrm{H_3C-O-CH_3$}$$

Question 1

Which of the following best describes the four major classes of biomacromolecules found in the human body?

Accepted Answer

Proteins, lipids, carbohydrates, nucleic acids

Question 2

Which class of biomolecules is primarily responsible for forming the structure of cellular membranes, as shown in the second image?

Accepted Answer

Lipids

Question 3

Which of the following functional groups can act as hydrogen bond donors?

Accepted Answer

Amine group, amide group, thiol group

Question 4

Which of the following best describes a chiral carbon?

Accepted Answer

A carbon atom bonded to four different chemical groups or atoms

Question 5

Which of the following is an example of a constitutional isomer?

Accepted Answer

$$\mathrm{H_3C-CH_2$-OH}$$ 	ext{ and } $$\mathrm{H_3C-O-CH_3$}$$

Question 6

Which class(es) of amino acids have side chains that can form hydrogen bonds with water?

Accepted Answer

Neutral polar, acidic, and basic

Question 7

At physiological pH (pH 7.0), what is the charge state of the backbone functional groups of an amino acid?

Accepted Answer

The amine has a positive charge and the carboxylic acid has a negative charge

Question 8

Which of the following amino acids is considered shape-determining due to its unique side chain structure?

Accepted Answer

Proline

Question 9

Which of the following best describes a zwitterion?

Accepted Answer

A molecule with both a positive and a negative charge but overall neutral

Question 10

Which of the following statements about the primary structure of a protein is correct?

Accepted Answer

It is the sequence of amino acids linked by peptide bonds, written from N-terminus to C-terminus

Question 11

Which bond forms between the carboxyl group of one amino acid and the amine group of another during protein synthesis?

Accepted Answer

Peptide (amide) bond

Question 12

Which class of amino acids prefers to have their side chains in a hydrophobic environment?

Accepted Answer

Nonpolar

Question 13

Which of the following interactions is primarily responsible for stabilizing the secondary structure of proteins such as alpha helices and beta sheets?

Accepted Answer

Hydrogen bonds forming between peptide bonds

Question 14

Which of the following is a real-life example of a protein with quaternary structure?

Accepted Answer

Hemoglobin

Question 15

Which of the following amino acids can form disulfide bonds, contributing to the stabilization of tertiary and quaternary protein structures?

Accepted Answer

Cysteine

Question 16

Which of the following best explains why proteins fold into specific three-dimensional shapes?

Accepted Answer

The hydrophobic effect causes nonpolar side chains to cluster away from water, while polar and charged side chains interact with water and each other

Question 17

Which of the following statements about isomers is correct?

Accepted Answer

Enantiomers are stereoisomers that are non-superimposable mirror images

Question 18

Which of the following amino acids is NOT classified as essential?

Accepted Answer

Glycine

Question 19

Which of the following protein classes is responsible for catalyzing biochemical reactions in the body?

Accepted Answer

Enzymes

Question 20

Which of the following statements about amino acids at physiological pH is correct?

Accepted Answer

All amino acids exist as zwitterions at pH 7.4

lec 8 Proteins and Their Amino Acid Building Blocks: Structure and Function

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