Question 1

Which of the following amino acids is both aromatic and nonpolar, and can be identified using the mnemonic for hydrophobic amino acids?

Accepted Answer

Phenylalanine

Question 2

A mutation causes the substitution of valine for glutamate in a protein. Which of the following best describes the change in the side chain's properties?

Accepted Answer

From electrically charged (acidic) to nonpolar, hydrophobic

Question 3

Which amino acid would most likely be found in the interior of a globular protein, away from water, and is also represented by the letter 'L' in the hydrophobic mnemonic?

Accepted Answer

Leucine

Question 4

A scientist is analyzing a protein using UV spectroscopy at 280 nm. Which amino acid, if present in high amounts, would most strongly contribute to the absorbance?

Accepted Answer

Tryptophan

Question 5

Which of the following amino acids is classified as basic and is included in the mnemonic 'Dragons Eat Knights Riding Horses'?

Accepted Answer

Lysine

Question 6

A protein is found to have a high content of serine and threonine. Which property is most likely increased in this protein due to these amino acids?

Accepted Answer

Ability to form hydrogen bonds with water

Question 7

Which amino acid is unique in that its side chain forms a covalent bond with the amino group, resulting in a rigid ring structure?

Accepted Answer

Proline

Question 8

A patient has a genetic disorder that affects the metabolism of methionine. Which property of methionine is most relevant to its role in protein structure?

Accepted Answer

It is nonpolar and hydrophobic

Question 9

Which of the following amino acids is most likely to participate in disulfide bond formation, stabilizing protein structure?

Accepted Answer

Cysteine

Question 10

If a protein's surface is rich in asparagine and glutamine, what can be inferred about its interaction with water?

Accepted Answer

It is likely to be hydrophilic

Question 11

Which amino acid is both aromatic and polar, and is represented by the letter 'Y' in the polar, uncharged mnemonic?

Accepted Answer

Tyrosine

Question 12

A protein is found to have a net negative charge at physiological pH. Which amino acids are most likely present in high amounts to contribute to this property?

Accepted Answer

Aspartate and Glutamate

Question 13

Which of the following best explains why glycine is often found in tight turns or flexible regions of proteins?

Accepted Answer

It is nonpolar and has the smallest side chain

Question 14

A researcher is designing a peptide to be embedded in a cell membrane. Which group of amino acids should be most prevalent in the transmembrane region?

Accepted Answer

Nonpolar, hydrophobic amino acids

Question 15

Which amino acid is represented by the letter 'W' in the hydrophobic mnemonic and is also aromatic?

Accepted Answer

Tryptophan

Question 16

A protein is mutated so that a lysine is replaced by a serine. Which of the following best describes the change in the side chain's properties?

Accepted Answer

From basic and charged to polar, uncharged

Question 17

Which of the following amino acids is most likely to be phosphorylated during cell signaling events?

Accepted Answer

Tyrosine

Question 18

A protein is found to be highly soluble in water. Which of the following amino acid compositions would most likely explain this property?

Accepted Answer

High in serine, threonine, and asparagine

Question 19

Which amino acid is most likely to be found at the active site of an enzyme that catalyzes acid-base reactions, due to its ability to accept or donate protons near physiological pH?

Accepted Answer

Histidine

Question 20

A protein is analyzed and found to contain a high proportion of proline residues. Which structural feature is most likely to be affected by this composition?

Accepted Answer

Alpha-helix formation

Amino Acid Properties and Classification: Study Guide

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