Question 1

Which of the following is the zwitterion form of L-alanine?

Accepted Answer

D

Question 2

What is the pI of valine, shown below? (the $\mathrm{p} K_{\mathrm{a}}$ 's are shown)

Accepted Answer

C

Question 3

Which of the following is the major product of the reaction shown below? (the $\mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}$ are shown)

Accepted Answer

A

Question 4

The Fischer projection shown below denotes a amino acid which has the configuration.

Accepted Answer

The answer of The Fischer projection shown below denotes a...

Question 5

What is the total number of different tripeptides which can result from three different L-amino acids?

Accepted Answer

Since there are three different L-amino acids and each position in the tripeptide can be occupied by any of the three amino acids, the total number of different tripeptides is calculated by multiplying the number of choices for each position: 3 (for the first position) * 3 (for the second position) * 3 (for the third position) = 27. However, the question specifies "different" tripeptides, implying a consideration of permutations without repetition. Therefore, the correct calculation should be a permutation of 3 items taken 3 at a time, which is 3! (3 factorial) = 3*2*1 = 6.

Question 6

What is the net charge on L-aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ at a pH of 11.0 ?

Accepted Answer

The answer of What is the net charge on L-aspartic...

Question 7

In strongly acidic solution L-lysine is primarily a dication as shown below. As the $\mathrm{pH}$ is raised, which proton is lost to form the monocation?

Accepted Answer

The answer of In strongly acidic solution L-lysine is primarily...

Question 8

Linus Pauling is credited with describing the $\alpha$-helix structure of a polypeptide. The $\alpha$-helix is an example of a polypeptide's

Accepted Answer

The $\alpha$-helix is a form of secondary structure in proteins, characterized by a right-handed coil with backbone hydrogen bonds stabilizing the structure.

Question 9

What is the net charge on the dipeptide lys-asp at a $\mathrm{pH}$ of 1.0 ?
Aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$
Lysine ( $\left.\mathrm{R}=\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\right)$

Accepted Answer

At a pH of 1.0, both the amino and carboxyl groups at the ends of the dipeptide will be protonated, giving them positive and neutral charges, respectively. The side chain of aspartic acid (Asp) will be protonated and neutral, while the side chain of lysine (Lys) will be protonated, giving it a positive charge. Thus, the net charge is +2.

Question 10

A pentapeptide was found to contain the amino acids ala, gly, met, phe, and ser. Partial hydrolysis of the pentapeptide gave the dipeptides gly-ser, met-phe, ala-gly, and ser-met. What is the sequence of the pentapeptide?

Accepted Answer

The dipeptides formed upon partial hydrolysis indicate the sequence of amino acids in the pentapeptide. The presence of ala-gly and gly-ser suggests that ala is at the beginning, followed by gly and then ser. The presence of ser-met and met-phe indicates that ser is followed by met, which is followed by phe, making the sequence ala-gly-ser-met-phe.

Question 11

Which of the following is the DNP derivative obtained from the reaction sequence shown below?

Accepted Answer

The answer of Which of the following is the DNP...

Question 12

Which one of the following reagents is used for the visual detection of amino acids?

Accepted Answer

Ninhydrin is widely used for the visual detection of amino acids because it reacts with the free amino groups to produce a deep blue or purple color, known as Ruhemann's purple, which is easily visible.

Question 13

Which one of the following is the final product of the reaction sequence shown below?

Accepted Answer

The answer of Which one of the following is the...

Question 14

Identify the missing starting reagent needed in the Strecker synthesis of isoleucine. (Assume you will get all the stereoisomers of isoleucine.)

Accepted Answer

The answer of Identify the missing starting reagent needed in...

Question 15

In aqueous solution, the artificial sweetener aspartame slowly converts to the cyclic compound shown below. Which of the following best describes this reaction?

Accepted Answer

The answer of In aqueous solution, the artificial sweetener aspartame...

Question 16

Which of the following is the abbreviated formula of the tetrapeptide shown below? (Hint: Remember to start at the $\mathrm{N}$-terminal end.)

Accepted Answer

The answer of Which of the following is the abbreviated...

Quiz 25: Amino Acids, Peptides, and Proteins

Which of the following is the zwitterion form of L-alanine?

What is the pI of valine, shown below? (the $\mathrm{p} K_{\mathrm{a}}$ 's are shown) $What is the pI of valine, shown below? (the \mathrm{p} K_{\mathrm{a}} 's are shown) A) 2.32 B) 4.81 C) 5.97 D) 9.62$

Which of the following is the major product of the reaction shown below? (the $\mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}$ are shown) $Which of the following is the major product of the reaction shown below? (the \mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }} are shown) A) B) C) D)$

The Fischer projection shown below denotes a amino acid which has the configuration.

What is the total number of different tripeptides which can result from three different L-amino acids?

What is the net charge on L-aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ at a pH of 11.0 ?

Linus Pauling is credited with describing the $\alpha$ -helix structure of a polypeptide. The $\alpha$ -helix is an example of a polypeptide's

What is the net charge on the dipeptide lys-asp at a $\mathrm{pH}$ of 1.0 ? Aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ Lysine ( $\left.\mathrm{R}=\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\right)$

A pentapeptide was found to contain the amino acids ala, gly, met, phe, and ser. Partial hydrolysis of the pentapeptide gave the dipeptides gly-ser, met-phe, ala-gly, and ser-met. What is the sequence of the pentapeptide?

Which of the following is the DNP derivative obtained from the reaction sequence shown below?

Which one of the following reagents is used for the visual detection of amino acids?

Which one of the following is the final product of the reaction sequence shown below?

Identify the missing starting reagent needed in the Strecker synthesis of isoleucine. (Assume you will get all the stereoisomers of isoleucine.)

Quiz 25: Amino Acids, Peptides, and Proteins

Which of the following is the zwitterion form of L-alanine?

What is the pI of valine, shown below? (the pKa\mathrm{p} K_{\mathrm{a}}pKa​ 's are shown)

Which of the following is the major product of the reaction shown below? (the pKa’s \mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}pKa​’s are shown)

The Fischer projection shown below denotes a amino acid which has the configuration.

What is the total number of different tripeptides which can result from three different L-amino acids?

What is the net charge on L-aspartic acid (R=−CH2CO2H) \left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right) (R=−CH2​CO2​H) at a pH of 11.0 ?

In strongly acidic solution L-lysine is primarily a dication as shown below. As the pH\mathrm{pH}pH is raised, which proton is lost to form the monocation?

Linus Pauling is credited with describing the α\alphaα -helix structure of a polypeptide. The α\alphaα -helix is an example of a polypeptide's

A pentapeptide was found to contain the amino acids ala, gly, met, phe, and ser. Partial hydrolysis of the pentapeptide gave the dipeptides gly-ser, met-phe, ala-gly, and ser-met. What is the sequence of the pentapeptide?

Which of the following is the DNP derivative obtained from the reaction sequence shown below?

Which one of the following reagents is used for the visual detection of amino acids?

Which one of the following is the final product of the reaction sequence shown below?

Identify the missing starting reagent needed in the Strecker synthesis of isoleucine. (Assume you will get all the stereoisomers of isoleucine.)

In aqueous solution, the artificial sweetener aspartame slowly converts to the cyclic compound shown below. Which of the following best describes this reaction?

Which of the following is the abbreviated formula of the tetrapeptide shown below? (Hint: Remember to start at the N\mathrm{N}N -terminal end.)

What is the pI of valine, shown below? (the $\mathrm{p} K_{\mathrm{a}}$ 's are shown) $What is the pI of valine, shown below? (the \mathrm{p} K_{\mathrm{a}} 's are shown) A) 2.32 B) 4.81 C) 5.97 D) 9.62$

Which of the following is the major product of the reaction shown below? (the $\mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}$ are shown) $Which of the following is the major product of the reaction shown below? (the \mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }} are shown) A) B) C) D)$

What is the net charge on L-aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ at a pH of 11.0 ?

Linus Pauling is credited with describing the $\alpha$ -helix structure of a polypeptide. The $\alpha$ -helix is an example of a polypeptide's