Chapter 4:Amino Acids Quiz

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The net charge of the zwitterion form of Gly is . A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

K

When a peptide bond is formed, an reacts with a carboxylate group. A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

E

At a pH above its pK , the phenol group of tyrosine is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

C

In the tripeptide Lys─Pro─Ile, there are charged groups at pH 7. A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

D Signup and view all the answers

At a pH below its pK , the -amino group of lysine is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

L Signup and view all the answers

At a pH below its pK , the -carboxylate group of Asp is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

B Signup and view all the answers

In the peptide Trp─Ser─Val, valine is at the
A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

G Signup and view all the answers

In the tripeptide Trp─Val─Phe, the N-terminal residue is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

N Signup and view all the answers

In the tripeptide Lys─Pro─Ile, the C-terminal residue is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

M Signup and view all the answers

Biological systems usually produce a single enantiomer, whereas chemical synthesis produces a A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

I Signup and view all the answers

GABA is a neurotransmitter derived from A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

A Signup and view all the answers

Glutathione is a tripeptide containing a central. residue. A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

J Signup and view all the answers

In the early 1930’s William Rose fed laboratory rats a mixture of all 19 amino acids known to be present in proteins. He observed that his rats lost weight. This observation led to the discovery of _ as the 20th amino acid found in proteins.

Thr Signup and view all the answers

What percentage of the 20 amino acids is considered to be nutritionally essential to lab animals?

50% Signup and view all the answers

About half of the 20 amino acids are called essential because

our bodies cannot synthesize them and therefore they need to be present in our diet. Signup and view all the answers

Which amino acid does not have a primary -amino group?

proline Signup and view all the answers

Which of the following statements is true?

Purines and pyrimidines can be derived from amino acids. Signup and view all the answers

Which of the following amino acids is the least abundant in proteins?

W Signup and view all the answers

Zwitterions are

ions that bear both negatively and positively charged groups. Signup and view all the answers

The formation of a dipeptide from two amino acids involves

loss of water. Signup and view all the answers

Which of the following amino acids has a charged polar side chain at pH 7.0?

Glu Signup and view all the answers

Which of the following tripeptides carries a net positive charge at pH 7.0?

Leu─Lys─Gly Signup and view all the answers

Which of the following amino acids has a sulfur atom in its side chain?

Met Signup and view all the answers

Which of the following amino acids does not have an ionizable side chain

Asn Signup and view all the answers

Which of the following amino acids has an uncharged polar side chain at pH 7.0?

Thr Signup and view all the answers

The ionization of amino acids depends on the pH and the pK s of the ionizable groups. The pK and pK for the amino acid shown above are 2.1 and 8.8, respectively. At what pH is the amino acid ionized predominantly as shown?

1.0 Signup and view all the answers

The pK1 , pK 2, and pKr for the amino acid arginine are 1.8, 9.0, and 12.5, respectively.

At pH 7.0 arginine would be charged predominantly as follows:

-carboxylate −1, -amino +1, guanidino +1, net charge +1 Signup and view all the answers

The pK1 , pK 2, and pKr for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively.

At pH 7.0, aspartic acid would be charged predominantly as follows:

-carboxylate −1, -amino +1, -carboxylate −1, net charge −1 Signup and view all the answers

The pK 1, pK2 , and pK rfor the amino acid glutamate are 2.1, 9.5, and 4.1, respectively.

At pH 11.0, glutamate would be charged predominantly as follows:

-carboxylate −1, -amino 0, -carboxylate −1, net charge −2 Signup and view all the answers

While proteins are usually composed of linear chains of amino acids, branched chains of amino acids and internally cross-linked chains can be found in certain proteins. Polypeptide chains are most commonly linked to each other through

disulfide bonds. Signup and view all the answers

The disulfide bond between two cysteine molecules

is a covalent bond formed by oxidation. Signup and view all the answers

The tripeptide glycylarginylglutamate contains four ionizable groups with pK s of 2.1, a 4.1 9.8, and 12.5. Calculate the pI for this molecule.

7.0 Signup and view all the answers

The tripeptide alanyllysylaspartate contains four ionizable groups with pK s of 2.0, 3.9, a 9.9, and 10.5. Calculate the pI for this molecule.

none of the above Signup and view all the answers

The isoelectronic point of an amino acid is the point where

the amino acid carries no net electrical charge. Signup and view all the answers

The side-chains of amino acids have

different pK s in peptides as compared to the free amino acids Signup and view all the answers

The peptide AYDG has an N-terminal residue.

alanine Signup and view all the answers

Which of the following tripeptides would be expected to be the most hydrophobic?

GYA Signup and view all the answers

What is the three-letter abbreviation for the peptide valylarginylisoleucine?

Val─Arg─Ile Signup and view all the answers

Ribosomes use L amino acids to synthesize proteins. These amino acids are called “L” because

they have a configuration of groups around the C that can be related to the configuration of groups around the asymmetric carbon in L-glyceraldehyde. Signup and view all the answers

Ribosomes use L amino acids to synthesize proteins. These amino acids are called “L” because

None of the above Signup and view all the answers

Which of the amino acids represented below has two chiral centers?

Ile Signup and view all the answers

All the standard amino acids except are optically active.

Fly Signup and view all the answers

The character of most standard amino acids causes solutions of amino acids to rotate the plane of polarized light.

Chrial Signup and view all the answers

All amino acids derived from proteins have the same stereochemical conformation as.

L-glyceraldehyde. Signup and view all the answers

Typically, modified amino acids, those with side chain modifications that are present in proteins

are formed by modification of standard side chain residues after the protein is synthesized. Signup and view all the answers

An amide bond between a side-chain carboxylate and an -amino group is also called a(n)

isopeptide bond. Signup and view all the answers

Chapter 4:Amino Acids Quiz

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Questions and Answers

The net charge of the zwitterion form of Gly is . A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

When a peptide bond is formed, an reacts with a carboxylate group. A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

At a pH above its pK , the phenol group of tyrosine is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

In the tripeptide Lys─Pro─Ile, there are charged groups at pH 7. A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

At a pH below its pK , the -amino group of lysine is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

At a pH below its pK , the -carboxylate group of Asp is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

In the peptide Trp─Ser─Val, valine is at the A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

In the tripeptide Trp─Val─Phe, the N-terminal residue is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

In the tripeptide Lys─Pro─Ile, the C-terminal residue is A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

GABA is a neurotransmitter derived from A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

Glutathione is a tripeptide containing a central. residue. A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

In the early 1930’s William Rose fed laboratory rats a mixture of all 19 amino acids known to be present in proteins. He observed that his rats lost weight. This observation led to the discovery of _ as the 20th amino acid found in proteins.

What percentage of the 20 amino acids is considered to be nutritionally essential to lab animals?

About half of the 20 amino acids are called essential because

Which amino acid does not have a primary -amino group?

Which of the following statements is true?

Which of the following amino acids is the least abundant in proteins?

Zwitterions are

The formation of a dipeptide from two amino acids involves

Which of the following amino acids has a charged polar side chain at pH 7.0?

Which of the following tripeptides carries a net positive charge at pH 7.0?

Which of the following amino acids has a sulfur atom in its side chain?

Which of the following amino acids does not have an ionizable side chain

Which of the following amino acids has an uncharged polar side chain at pH 7.0?

The ionization of amino acids depends on the pH and the pK s of the ionizable groups. The pK and pK for the amino acid shown above are 2.1 and 8.8, respectively. At what pH is the amino acid ionized predominantly as shown?

The pK1 , pK 2, and pKr for the amino acid arginine are 1.8, 9.0, and 12.5, respectively. At pH 7.0 arginine would be charged predominantly as follows:

The pK1 , pK 2, and pKr for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively. At pH 7.0, aspartic acid would be charged predominantly as follows:

The pK 1, pK2 , and pK rfor the amino acid glutamate are 2.1, 9.5, and 4.1, respectively. At pH 11.0, glutamate would be charged predominantly as follows:

While proteins are usually composed of linear chains of amino acids, branched chains of amino acids and internally cross-linked chains can be found in certain proteins. Polypeptide chains are most commonly linked to each other through

The disulfide bond between two cysteine molecules

The tripeptide glycylarginylglutamate contains four ionizable groups with pK s of 2.1, a 4.1 9.8, and 12.5. Calculate the pI for this molecule.

The tripeptide alanyllysylaspartate contains four ionizable groups with pK s of 2.0, 3.9, a 9.9, and 10.5. Calculate the pI for this molecule.

The isoelectronic point of an amino acid is the point where

The side-chains of amino acids have

The peptide AYDG has an N-terminal residue.

Which of the following tripeptides would be expected to be the most hydrophobic?

What is the three-letter abbreviation for the peptide valylarginylisoleucine?

Ribosomes use L amino acids to synthesize proteins. These amino acids are called “L” because

Ribosomes use L amino acids to synthesize proteins. These amino acids are called “L” because

Which of the amino acids represented below has two chiral centers?

All the standard amino acids except are optically active.

The character of most standard amino acids causes solutions of amino acids to rotate the plane of polarized light.

All amino acids derived from proteins have the same stereochemical conformation as.

Typically, modified amino acids, those with side chain modifications that are present in proteins

An amide bond between a side-chain carboxylate and an -amino group is also called a(n)

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The Glycine Quiz

Glycine

Biosynthesis of Nonessential Amino Acids

Single carbon metabolism

In the peptide Trp─Ser─Val, valine is at the
A) glutamate B) uncharged C) deprotonated D) three E) amino group F) two G) C-terminus H) lysine I) racemic mixture J) cysteine K) zero L) protonated M) isoleucine N) tryptophan O ) phenylalanine P) N-terminus

The pK1 , pK 2, and pKr for the amino acid arginine are 1.8, 9.0, and 12.5, respectively.

At pH 7.0 arginine would be charged predominantly as follows:

The pK1 , pK 2, and pKr for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively.

At pH 7.0, aspartic acid would be charged predominantly as follows:

The pK 1, pK2 , and pK rfor the amino acid glutamate are 2.1, 9.5, and 4.1, respectively.

At pH 11.0, glutamate would be charged predominantly as follows: