Deck 25: Amino Acids, Peptides, and Proteins

Question 1

Which one of the following amino acid does not have an L-isomer?

A)valine
B)alanine
C)leucine
D)glycine
E)none of these

Answer 1

glycine

Question 2

Which of the following is a predominant form of asparagine at physiological pH?

A)I
B)II
C)III
D)IV
E)V

Answer 2

V

Question 3

Proteins found in humans have all amino acids with ____configuration.

A)D
B)L
C)meso
D)A & B
E)none of these

Answer 3

L

Question 4

When more than fifty amino acids are connected to each other,they form _________.

A)a tripeptide
B)a protein
C)a polypeptide
D)a tetrapeptide
E)none of these

Question 5

Provide the structure of a predominant form of alanine at pH 2?

Question 6

When four amino acids are connected to each other,they form ____________.

A)a tripeptide
B)a protein
C)a polypeptide
D)a tetrapeptide
E)none of these

Question 7

Which of the following is a predominant form of lysine at pH 14?

A)I
B)II
C)III
D)IV
E)V

Question 8

Amino acids are connected to each other by____________.

A)an ether linkage
B)a peptide linkage
C)an ester linkage
D)none of these

Question 9

When thirty amino acids are connected to each other,they form ____________.

A)a tripeptide
B)a protein
C)a polypeptide
D)a tetrapeptide
E)none of these

Question 10

Which of the following naturally occurring amino acids do not have S configuration?

A)alanine
B)cysteine
C)tyrosine
D)isoleucine
E)none of these

Question 11

Which of the following amino acids have an acidic side chain?

A)I & III
B)I,II & III
C)IV & V
D)II,IV & V
E)all of these

Question 12

Provide the structure of a predominant form of valine at pH 10?

Question 13

Which of the following is a correct structure for D-leucine?

A)I
B)II
C)III
D)IV
E)V

Question 14

Which of the following is a correct structure for L-valine?

A)I
B)II
C)III
D)IV
E)V

Question 15

Which of the following amino acids have a basic side chain?

A)I & II
B)I,II & IV
C)III & V
D)I,II,III & IV
E)all of these

Question 16

Which of the following is a predominant form of aspartic acid at pH 1?

A)I
B)II
C)III
D)IV
E)V

Question 17

Which of the following amino acids is achiral?

A)alanine
B)leucine
C)glycine
D)phenylalanine
E)none of these

Question 18

Which of the following is a predominant form of arginine at pH 2?

A)I
B)II
C)III
D)IV
E)V

Question 19

In $\alpha$ -amino acids the amino and carboxylic acid groups are separated by ____,

A)two carbon atoms
B)one carbon atom
C)peptide linkage
D)amide linkage
E)none of these

Question 20

Which of the following is a predominant form of serine at physiological pH?

A)I
B)II
C)III
D)IV
E)V

Question 21

Which of the following amino acids have a pI around pH 10?

A)I
B)II
C)III
D)IV
E)V

Question 22

Which amino acid is produced from the following reaction sequence?

A)alanine
B)valine
C)leucine
D)isoleucine
E)none of these

Question 23

Which amino acid is produced from the following reaction sequence?

A)alanine
B)valine
C)leucine
D)isoleucine
E)none of these

Question 24

Which amino acid is produced from the following reaction sequence?

A)alanine
B)valine
C)leucine
D)isoleucine
E)none of these

Question 25

How will you prepare glycine staring with ethanol and using a Hell-Volhard-Zelinski reaction?

Question 26

Which amino acid is produced from the following reaction sequence?

A)alanine
B)valine
C)leucine
D)isoleucine
E)none of these

Question 27

Which of the following amino acids will migrate towards the cathode at pH 7?
Glycine: pI=6.0
Lysine: pI=9.7

Question 28

Which amino acid is produced from the following reaction sequence?

A)alanine
B)valine
C)leucine
D)isoleucine
E)none of these

Question 29

Which of the following amino acids will migrate towards the anode at pH 6?
Phenylalanine: pI = 5.5
Leucine: pI = 6

Question 30

Which of the following is used to detect the presence of amino acids using chromatography?

A)2,4-DNP
B)methyl orange
C)phenolphthalein
D)ninhydrin
E)none of these

Question 31

Which of the following is true about the amino acids with isoelectric point around pH 10?

A)the side chain must be acidic
B)the side chain must be basic
C)the side chain must be polar
D)the side chain must be non polar
E)none of these

Question 32

How will you prepare phenylalanine using a Hell-Volhard-Zelinski reaction?

Question 33

Which of the following amino acids have a pI around pH 3?

A)I
B)II
C)III
D)IV
E)V

Question 34

Which of the following is true about the amino acids with isoelectric point around pH 3?

A)the side chain must be acidic
B)the side chain must be basic
C)the side chain must be polar
D)the side chain must be non polar
E)none of these

Question 35

Provide the structure of the amino acid produced from the following reaction sequence.

Question 36

Which of the following amino acids will migrate towards the anode at pH 7?
Glycine: pI=6.0
Lysine: pI=9.7

Question 37

Which of the following amino acids will not migrate towards the cathode/anode at pH 6?
Phenylalanine: pI = 5.5
Leucine: pI = 6

Question 38

Which of the following amino acids will move the farthest when subjected to electrophoresis at pH 7?

A)I
B)II
C)III
D)II & III
E)none of these

Question 39

Provide the structure of the amino acid produced from the following reaction sequence.

Question 40

Which amino acid is produced from the following reaction sequence?

A)alanine
B)valine
C)leucine
D)isoleucine
E)none of these

Question 41

What is the correct sequence of amino acids for the following tripeptide?

A)Ser-Met-Ile
B)Ser-Cys-Ile
C)Thr-Met-Leu
D)Thr-Cys-Leu
E)none of these

Question 42

What is the correct sequence of amino acids for the following tripeptide?

A)Leu-Phe-Ala
B)Val-Phe-Ala
C)Ile-Tyr-Leu
D)Leu-Tyr-Val
E)none of these

Question 43

Which of the following aldehydes would produce glycine using a Strecker synthesis?

A)methanal
B)ethanal
C)propanal
D)none of these

Question 44

Which of the following alkenes is used to prepare isoleucine using an asymmetric catalytic hydrogenation?

A)I
B)II
C)III
D)IV
E)none of these

Question 45

Which amino acid is produced from the following reaction?

A)methionine
B)serine
C)cysteine
D)lysine
E)none of these

Question 46

Which of the following is a correct bond-line structure for a tripeptide Ser-Lys-Cys?

A)I
B)II
C)III
D)IV
E)none of these

Question 47

Edman degradation removes the amino acid residue from the _______ of the peptide.

A)C-terminus end
B)N-terminus end
C)middle end
D)none of these

Question 48

Which of the following is a correct bond-line structure for a tripeptide Val-Asp-Ala?

A)I
B)II
C)III
D)IV
E)none of these

Question 49

Which amino acid is produced from the following reaction?

A)methionine
B)serine
C)cysteine
D)lysine
E)none of these

Question 50

Draw a bond-line structure for the tetrapetide Ala-Ser-Cys-Phe.

Question 51

Draw a bond-line structure for the tetrapetide Ile-Ser-Leu-Gly.

Question 52

Provide the reagents necessary to prepare phenylalanine using a Strecker synthesis.

Question 53

Which of the following reagent(s)is(are)used to remove the N-terminus amino acid residue using Edman degradation?

A)I
B)II
C)III
D)IV
E)none of these

Question 54

Disulfide bridges are formed by:

A)oxidation of thiol groups
B)joining cysteine residues within a peptide
C)joining cysteine residues between two strands of a peptide
D)all of these

Question 55

Provide the structure of the amino acid produced from the following reaction.

Question 56

What is the three letter abbreviation for the sequencing of the following peptide?

Question 57

Provide the structure of the amino acid produced from the following reaction sequence.

Question 58

Which of the following results after single Edman degradation of the tetrapeptide Gly-Phe-Tyr-Ser?

A)Gly-Phe-Tyr
B)Tyr-Ser
C)Phe-Tyr-Ser
D)Gly-Phe
E)none of these

Question 59

Which of the following aldehydes would produce isoleucine using a Strecker synthesis?

A)3-methylbutanal
B)2-methylbutanal
C)2-methylpropanal
D)propanal
E)none of these

Question 60

The s-trans conformation of a peptide bond is more stable than the s-cis conformation because:

A)there is a restricted rotation around the peptide bond
B)rotation is allowed around the peptide bond
C)it has reduced steric hindrance
D)none of these

Question 61

Chymotrypsin,a digestive enzyme,catalyzes the hydrolysis of the peptide bond at the carboxyl end of which of the following amino acids?

A)phenylalanine
B)tyrosine
C)tryptophan
D)histidine
E)A,B & C

Question 62

Which of the following results after three steps of Edman degradation of the heptapeptide Lys-His-Gly-Phe-Tyr-Ser-Ala?

A)Lys-His-Gly
B)Phe-Tyr-Ser-Ala
C)Tyr-Ser-Ala
D)Lys-His-Gly-Phe
E)none of these

Question 63

Provide a stepwise synthesis for the dipeptide Ser-Phe.

Question 64

Which of the following is the correct sequence of the tetrapeptide that is formed by the following reaction sequence?

A)Cys-Ala-Phe-Ser
B)Cys-Phe-Ala-Ser
C)Ser-Ala-Phe-Cys
D)Ser-Phe-Ala-Cys
E)none of these

Question 65

Which of the following dipeptides is formed when leucine is treated with (Boc)₂O and glycine is treated with benzyl alcohol first and then reacted in the presence of DCC followed by treatment with trifluoroacetic acid and aqueous NaOH?

A)Gly-Leu
B)Gly-Gly
C)Leu-Gly
D)Leu-Leu
E)all of these

Question 66

The method developed by ______is used to prepare larger peptides.

A)Edman
B)Strecker
C)Merrifield
D)none of these

Question 67

Which of the following tetrapeptides is not cleaved by trypsin?

A)Gly-Lys-Cys-Phe
B)Cys-Ala-Arg-Ser
C)Gly-Ser-Ile-Lys
D)Ala-Lys-Tyr-Arg
E)none of these

Question 68

Which of the following tetrapeptides is not cleaved by chymotrypsin?

A)Gly-Lys-Cys-Trp
B)Cys-Tyr-Arg-Phe
C)Phe-Ser-Ile-Lys
D)Ala-Trp-Tyr-Arg
E)none of these

Question 69

Trypsin,a digestive enzyme,catalyzes the hydrolysis of the peptide bond at the carboxyl end of which of the following amino acids?

A)arginine
B)lysine
C)histidine
D)tryptophan
E)A & B

Question 70

Which of the following fragments are formed when the following peptide is cleaved using chymotrypsin? Gly-Lys-Cys-Phe-Ile-Val-Tyr-Ala-Ser

A)Gly-Lys-Cys,Phe-Ile-Val,Tyr-Ala-Ser
B)Gly-Lys-Cys-Phe,Ile-Val-Tyr,Ala-Ser
C)Gly-Lys-Cys-Phe,Ile-Val,Tyr-Ala-Ser
D)Gly-Lys-Cys,Phe,Ile-Val-Tyr,Ala-Ser
E)none of these

Question 71

Which of the following tripeptides is formed when alanine is treated with (Boc)₂O and proline is treated with benzyl alcohol first and then reacted in the presence of DCC followed by treatment with aqueous NaOH.The dipeptide is then reacted with an ester of leucine in the presence of DCC followed by treatment with trifluoroacetic acid and aqueous NaOH?

A)Ala-Pro-Leu
B)Pro-Ala-Leu
C)Leu-Ala-Pro
D)Pro-Leu-Ala
E)all of these

Question 72

Which of the following dipeptides is formed when tyrosine is treated with (Boc)₂O and proline is treated with benzyl alcohol first and then reacted in the presence of DCC followed by treatment with trifluoroacetic acid and aqueous NaOH?

A)Tyr-Pro
B)Pro-Tyr
C)Pro-Pro
D)Tyr-Tyr
E)all of these

Question 73

Which of the following dipeptides is formed when alanine and valine are reacted in the presence of dicyclohexylcarbodiimide (DCC)?

A)Ala-Val
B)Val-Ala
C)Ala-Ala
D)Val-Val
E)all of these

Question 74

Which of the following fragments are formed when the following peptide is cleaved using trypsin? Gly-Lys-Cys-Phe-Ile-Val-Tyr-Ala-Ser

A)Gly,Lys-Cys,Phe-Ile-Val,Tyr-Ala-Ser
B)Gly-Lys,Cys-Phe-Ile-Val-Tyr-Ala-Ser
C)Gly-Lys-Cys-Phe,Ile-Val-Tyr-Ala-Ser
D)Gly-Lys,Cys,Phe-Ile-Val,Tyr-Ala-Ser
E)none of these

Question 75

Which of the following reagents is used to protect the amino group in the selective synthesis of a dipeptide ala-val?

A)I
B)II
C)III
D)IV
E)V

Question 76

A peptide with 12 amino acid residues produced the following fragments when treated with trypsin and chymotrypsin.Edman degradation of this peptide produced the phenylthiohydantoin derivative of glycine.What is the structure of this peptide?
Trypsin: Gly-Leu-Phe-Arg,Cys-Tyr-Ile-Gly,Val-Trp-Ser-Lys
Chymotrypsin: Gly-Leu-Phe,Ser-Lys-Cys-Tyr,Ile-Gly,Arg-Val-Trp,

Question 77

Provide the steps necessary to prepare the tetrapeptide Thr-Val-Ile-Met using the Merrifield synthesis.

Question 78

Which of the following is the correct sequence for the pentapeptide that is formed by the following reaction sequence?

A)Leu-Lys-Ala-Gly-Met
B)Met-Gly-Ala-Lys-Leu
C)Cys- Gly-Ala-Lys-Leu
D)none of these

Question 79

Which of the following tripeptides is formed when serine is treated with (Boc)₂O and threonine is treated with benzyl alcohol first and then reacted in the presence of DCC followed by treatment with aqueous NaOH.The dipeptide is then reacted with an ester of isoleucine in the presence of DCC followed by treatment with trifluoroacetic acid and aqueous NaOH?

A)Ser-Tyr-Ile
B)Ser-Thr-Ile
C)Ile-Ser-Thr
D)Ile-Ser-Tyr
E)none of these

Question 80

Which of the following is the correct sequence for the pentapeptide that is formed by the following reaction sequence?

A)Ser-Thr-Pro-Lys-Leu
B)Leu-Lys-Pro-Thr-Ser
C)Thr-Thr- Pro-Lys-Leu
D)none of these