Question 1

At physiological pH, how do the behaviors of acidic and basic amino acids differ?

Accepted Answer

Acidic amino acids donate hydrogen ions, while basic amino acids accept them.

Question 2

What is the distinctive feature of cysteine's R group?

Accepted Answer

It contains a sulfhydryl group.

Question 3

How does isomerism in isoleucine affect its structure compared to leucine?

Accepted Answer

Isoleucine has the same atoms as leucine but arranged differently.

Question 4

Which concept is essential for understanding the Henderson-Hasselbalch equation?

Accepted Answer

The concept of acid-base equilibrium.

Question 5

In determining the R and S configuration, which group is typically assigned the lowest priority?

Accepted Answer

Hydrogen

Question 6

A vegetarian diet lacking in which essential amino acid could lead to a deficiency if not properly supplemented?

Accepted Answer

Lysine

Question 7

Why is it recommended to focus on memorizing the eight phonetic-origin one-letter codes?

Accepted Answer

Because they represent the most hydrophobic amino acids.

Question 8

How does the isoelectric point affect a molecule's behavior in an electric field?

Accepted Answer

The molecule does not migrate because it has no net charge.

Question 9

Which property is unique to ionizable R groups compared to non-ionizable R groups?

Accepted Answer

Ability to participate in acid-base reactions.

Question 10

What makes the mnemonic 'a spare gene chilling on 3 tropical islands' effective for memorizing amino acid codes?

Accepted Answer

It uses phonetic similarities to create memorable associations.

Question 11

How does the R group of cysteine influence protein structure?

Accepted Answer

It forms disulfide bonds.

Question 12

How does the pH of a solution relative to the pKa of an amino group affect its protonation state?

Accepted Answer

If $$pH \u003c pK_a$$, the amino group is protonated.

Question 13

Why are polar amino acids important in the formation of protein secondary structures?

Accepted Answer

They can form hydrogen bonds that stabilize alpha helices and beta sheets.

Question 14

A patient with a genetic mutation that prevents the formation of disulfide bonds would most likely have defects in which aspect of protein structure?

Accepted Answer

Tertiary structure

Question 15

Which equation is used to calculate the pH of a buffer solution containing a weak acid and its conjugate base?

Accepted Answer

$$pH = pK_a + \log_{10} \left( \frac{[A^-]}{[HA]} \right)$$

Question 16

Which amino acid is most likely to be found in the hydrophobic core of a globular protein?

Accepted Answer

Valine

Question 17

A solution contains a mixture of amino acids at pH 7. Which amino acid is most likely to have a net negative charge at this pH?

Accepted Answer

Aspartic acid

Question 18

Which of the following best explains why proline disrupts alpha helices in proteins?

Accepted Answer

Proline's side chain forms a rigid ring that limits backbone flexibility.

Question 19

A patient is diagnosed with a metabolic disorder that impairs the absorption of basic amino acids. Which amino acid is most likely to be deficient in this patient?

Accepted Answer

Arginine

Question 20

Which of the following statements about peptide bonds is correct?

Accepted Answer

Peptide bonds are formed by a condensation reaction between the carboxyl group of one amino acid and the amino group of another.

Amino Acids: Structure, Properties, and Roles in Protein Biochemistry

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