Deck 25: Amino Acids, Peptides, and Proteins

Question 1

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

Answer 1

a protein

Question 2

Which of the following amino acids is achiral?

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

Answer 2

glycine

Question 3

How many different amino acids are abundantly found in proteins?

A) 10
B) 16
C) 20
D) 40
E) none of these

Answer 3

20

Question 4

Which of the following statements is true about $\alpha$ -amino acids?

A) the amino and carboxylic acid groups are separated by one carbon atom
B) the amino group is connected to a carbon atom that is $\alpha$ to the carboxylic acid group
C) the $\alpha$ carbon can be a chirality center
D) all of these are true

Question 5

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

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

Question 6

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

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

Question 7

Amino acids are connected to each other by____________.

A) an ether linkage
B) a peptide linkage
C) an ester linkage
D) an amide linkage
E) both B and D

Question 8

Which one of the following amino acids contain an amide side chain?

A) cysteine
B) serine
C) glutamine
D) leucine
E) proline

Question 9

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

A) a tripeptide
B) a protein
C) a polypeptide
D) a tetrapeptide
E) a dipeptide

Question 10

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 11

_______________ are certain proteins that serve as catalysts for most of the reactions in living cells.

Question 12

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

A) a tripeptide
B) a protein
C) a polypeptide
D) a tetrapeptide
E) a dipeptide

Question 13

Which one of the following amino acids contain a sulfur atom?

A) cysteine
B) serine
C) glutamine
D) leucine
E) proline

Question 14

Which of the following amino acids contain a polar side chain?

A) tyrosine
B) proline
C) leucine
D) tryptophan
E) glycine

Question 15

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

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

Question 16

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

A) a tripeptide
B) a protein
C) a polypeptide
D) a tetrapeptide
E) a dipeptide

Question 17

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

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

Question 18

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 19

Which one of the following amino acids contain a hydroxyl side chain?

A) cysteine
B) serine
C) glutamine
D) leucine
E) proline

Question 20

Proteins found in humans have all amino acids with ____configuration.

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

Question 21

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

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

Question 22

Which of the following amino acids is not an essential amino acid?

A) phenylalanine
B) glycine
C) isoleucine
D) threonine
E) valine

Question 23

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

Question 24

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

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

Question 25

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

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

Question 26

Amino acids are considered amphoteric because _____________.

A) they only react with acids
B) they only react with bases
C) they react with both acids and bases
D) they do not react with acids or bases
E) none of these

Question 27

Draw the Fischer projection for L-cysteine and assign the configuration (R/S) at the chirality center.

Question 28

Draw the Fischer projection for D-serine and assign the configuration (R/S) at the chirality center.

Question 29

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

Question 30

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 31

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

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

Question 32

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 33

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

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

Question 34

Which of the following is a zwitterion for alanine?

A) I
B) II
C) III
D) IV
E) both I and IV

Question 35

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

Question 36

Draw the Fischer projection for L-aspartic acid and assign the configuration (R/S) at the chirality center.

Question 37

Which of the following amino acids is the smallest?

A) tyrosine
B) proline
C) leucine
D) tryptophan
E) glycine

Question 38

An amino acid can exist as a ________, which is a dipolar ion that carries both positive and negative charge.

A) cation
B) anion
C) zwitterion
D) none of these

Question 39

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

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

Question 40

Which of the following amino acids is the largest amino acid with a nonpolar side chain?

A) tyrosine
B) proline
C) leucine
D) tryptophan
E) glycine

Question 41

Provide the structure of the predominant form of the following amino acids at pH 7 and predict the migration towards anode or cathode during electrophoresis.

Question 42

Which amino acid is produced from the following reaction sequence?

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

Question 43

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

Question 44

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

Question 45

Which amino acid is produced from the following reaction sequence?

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

Question 46

Separation of amino acids using electrophoresis is mainly based on ______.

A) differences in the pI values
B) concentration
C) differences in pH values
D) none of these

Question 47

What is the pI of the following amino acid?

A) 5.56
B) 6.35
C) 9.74
D) 10.53
E) none of these

Question 48

Provide the structure of the predominant form of the following amino acids at pH 6 and predict the migration towards anode or cathode during electrophoresis.

Question 49

Which amino acid is produced from the following reaction sequence?

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

Question 50

Identify the compound that reacts with amino acids to form a fluorescent purple product.

A) 2,4-DNP
B) ninhydrin
C) methyl orange
D) methyl red
E) phenolphthalein

Question 51

What is the pI of the following amino acid?

A) 1.16
B) 4.81
C) 5.97
D) 9.62
E) none of these

Question 52

The pH at which the concentration of the zwitterionic form of an amino acid is at a maximum value is called the _______.

A) dipolar point
B) electric point
C) neutral point
D) isoelectric point
E) none of these

Question 53

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

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

Question 54

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) methyl red

Question 55

What is the pI of the following amino acid?

A) 2.76
B) 5.74
C) 6.62
D) 7.50
E) none of these

Question 56

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

Question 57

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

Question 58

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 and III
E) none of these

Question 59

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

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

Question 60

Which amino acid is produced from the following reaction sequence?

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

Question 61

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

A) methanal
B) ethanal
C) propanal
D) butanal

Question 62

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

Question 63

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

Question 64

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

Question 65

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

Question 66

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

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

Question 67

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

Question 68

Which amino acid is produced from the following reaction sequence?

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

Question 69

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

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

Question 70

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 71

In the Hell-Volhard-Zelinski reaction, the ___- carbon of the carboxylic acid is halogenated.

A) alpha
B) beta
C) gamma
D) delta
E) epsilon

Question 72

Which amino acid is produced from the following reaction?

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

Question 73

Which amino acid is produced from the following reaction?

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

Question 74

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

Question 75

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

Question 76

Which amino acid is produced from the following reaction sequence?

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

Question 77

Provide the reagents necessary to synthesize the following amino acid via the amidomalonate synthesis.

Question 78

Provide the reagents necessary to synthesize the following amino acid via the amidomalonate synthesis.

Question 79

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

Question 80

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