Deck 21: Proteins

Question 1

What are the basic structural units of proteins?

A) amino acids
B) monosaccharides
C) triglycerides
D) fatty acids

Answer 1

A

Question 2

Which of the following is a structural protein?

A) cellulose
B) collagen
C) hemoglobin
D) insulin

Answer 2

B

Question 3

Which of the following is an achiral amino acid?

A) proline
B) glycine
C) alanine
D) arginine

Answer 3

B

Question 4

How many naturally occurring amino acids are commonly found in proteins?

A) 10
B) 20
C) 25
D) 100

Question 5

Which of the following amino acids contains nitrogen in its side chain?

A) cysteine
B) glycine
C) proline
D) leucine

Question 6

Which of the following amino acid side chains is hydrophobic?

A) acidic
B) nonpolar
C) polar but neutral
D) none of these

Question 7

Which of the following is a function of proteins?

A) catalysis
B) movement
C) storage
D) all of these

Question 8

Which of the following proteins stimulates the formation of red blood cells in the body?

A) fibrinogen
B) collagen
C) casein
D) erythropoietin

Question 9

Which of the following proteins is a hormone?

A) casein
B) hemoglobin
C) insulin
D) all of these

Question 10

Which of the following amino acid side chains is hydrophobic?

A) acidic
B) basic
C) polar but neutral
D) none of these

Question 11

Identify a statement that is true of the functions of proteins.

A) Ferritin, a protein that is found in the liver, stores iron in the body.
B) Hemoglobin, a protein, carries oxygen from cells to the lungs.
C) Antigens are proteins that are produced by the body to counteract antibodies.
D) Keratin forms the skeletal muscles of the body.

Question 12

Which of the following amino acid side chains is hydrophilic?

A) acidic
B) basic
C) polar but neutral
D) all of these

Question 13

Which of the following proteins is associated with the storage of iron?

A) actin
B) ferritin
C) hemoglobin
D) insulin

Question 14

Which of the following are considered the most important biological compound?

A) vitamins
B) carbohydrates
C) lipids
D) proteins

Question 15

Which of the following proteins can assist in blood clotting?

A) insulin
B) erythropoietin
C) fibrinogen
D) ferritin

Question 16

Which of the following proteins is associated with the movement of muscles?

A) actin
B) ferritin
C) hemoglobin
D) insulin

Question 17

Which of the following amino acids is not optically active?

A) alanine
B) glycine
C) tryptophan
D) none, all of these are optically active

Question 18

What is the most important aspect of an amino acid's side chain?

A) its polarity
B) its shape
C) its size
D) none of these

Question 19

Which of the following statements is true of the water solubility of proteins?

A) Both fibrous and globular proteins are insoluble in water.
B) Both fibrous and globular proteins are soluble in water.
C) Fibrous proteins are insoluble in water.
D) Globular proteins are insoluble in water.

Question 20

Which of the following is not a fibrous protein?

A) actin
B) collagen
C) keratin
D) None, they are all fibrous proteins.

Question 21

Which of the following contains a disulfide bond?

A) alanine
B) cysteine
C) cystine
D) methionine

Question 22

What is the approximate isoelectric point (pI) of most amino acids?

A) 3
B) 6
C) 7
D) 10

Question 23

Which of the following pair of amino acids has basic side chains?

A) cysteine and glycine
B) cysteine and methionine
C) histidine and lysine
D) phenylalanine and tryptophan

Question 24

Which of the following is a β-hydroxy-α-amino acid?

A) asparagine
B) serine
C) tryptophan
D) none of these

Question 25

Which of the following amino acids has the lowest pI?

A) arginine
B) cysteine
C) glycine
D) glutamic acid

Question 26

Which of the following pair of amino acids has sulfur-containing side chains?

A) cysteine and glycine
B) cysteine and methionine
C) histidine and methionine
D) phenylalanine and tryptophan

Question 27

Which of the following amino acids has a hydroxyl side chain?

A) asparagine
B) glutamine
C) threonine
D) none of these

Question 28

Which of the following explains the unusually high melting points of amino acids?

A) their unusually high molecular weights
B) the polarity of their side chains
C) the presence of nitrogen atoms in their side chains
D) their existence as zwitterions in polar solvents

Question 29

Which of the following amino acids has the highest pI?

A) arginine
B) cysteine
C) glycine
D) glutamic acid

Question 30

Which of the following amino acids can be easily dimerized?

A) alanine
B) cysteine
C) glycine
D) methionine

Question 31

Which of the following is true of amino acids that are dissolved in water?

A) They exist in an un-ionized form at high pH.
B) They exist in an un-ionized form at low pH.
C) They exist in an un-ionized form only at a specific pH.
D) They do not exist in an un-ionized form at any pH.

Question 32

Which of the following statements is true of zwitterions?

A) They are positively charged.
B) They are negatively charged.
C) They are electrically neutral.
D) They are made up of basic amino acids.

Question 33

Which of the following statements is true of the isoelectric point of amino acids?

A) It is the same for all amino acids.
B) It is the pH at which an amino acid conducts electricity.
C) It is the pH at which an amino acid has equal numbers of positive and negative charges.
D) All of these statements are true.

Question 34

Which of the following pair of amino acids has nonpolar side chains?

A) cysteine and glycine
B) cysteine and methionine
C) histidine and methionine
D) phenylalanine and tryptophan

Question 35

Which of the following is true of an amino acid at a pH above its isoelectric point?

A) It will have a negative charge.
B) It will be electrically neutral.
C) It will have a positive charge.
D) It is impossible to predict the charge of an amino acid.

Question 36

Which of the following is true of an amino acid at a pH below its isoelectric point?

A) It will have a negative charge.
B) It will be electrically neutral.
C) It will have a positive charge.
D) It is impossible to predict the charge of an amino acid.

Question 37

Which of the following statements is true of all amino acids?

A) All amino acids have a D-isomer.
B) All amino acids have an L-isomer.
C) The amino group is attached to the carbon atom of the carboxyl group.
D) The amino group and the carbon of the carboxyl group are attached to the same carbon atom.

Question 38

Which of the following pair of amino acids has polar but neutral side chains?

A) cysteine and methionine
B) cysteine and serine
C) histidine and methionine
D) phenylalanine and tryptophan

Question 39

Which of the following diseases is associated with lower-than-normal levels of L-dopa?

A) Alzheimer's disease
B) Schizophrenia
C) Parkinson's disease
D) Bipolar disorder

Question 40

What determines the functions of amino acids?

A) their molecular weight
B) their side chain
C) both molecular weight and side chain
D) neither molecular weight nor side chain

Question 41

How many essential amino acids have acidic side chains?

A) 1
B) 2
C) 3
D) 4

Question 42

Which of the following types of chemical reaction is involved in the conversion of dopamine to epinephrine?

A) addition
B) reduction
C) decarboxylation
D) methylation

Question 43

Which of the following amino acids has a guanidino group in its side chain?

A) asparagine
B) glutamic acid
C) arginine
D) none of these

Question 44

Which of the following amino acids absorbs UV radiation at 280 nm?

A) phenylalanine
B) tryptophan
C) tyrosine
D) all of these

Question 45

What type of chemical reaction is involved in the conversion of cystine to cysteine?

A) addition
B) reduction
C) oxidation
D) substitution

Question 46

Neurotransmitters known as catecholamines are formed from which amino acid?

A) cysteine
B) threonine
C) tyrosine
D) valine

Question 47

Which pair of the amino acids is the precursors of norepinephrine and epinephrine?

A) aspartic acid and glutamic acid
B) cysteine and methionine
C) isoleucine and leucine
D) phenylalanine and tyrosine

Question 48

Which amino acid can be found in proteins in both its protonated and unprotonated forms?

A) alanine
B) glycine
C) histidine
D) phenylalanine

Question 49

Which of the following amino acids contains iodine atoms in its structure?

A) leucine
B) lysine
C) thyroxine
D) tyrosine

Question 50

What type of chemical reaction is involved in the formation of cystine from cysteine?

A) addition
B) reduction
C) oxidation
D) substitution

Question 51

How many essential amino acids have basic side chains?

A) 1
B) 2
C) 3
D) 4

Question 52

Which of the following amino acids is occasionally found in proteins?

A) asparagine
B) hydroxyproline
C) proline
D) serine

Question 53

Which of the following amino acids has an imidazole group side chain?

A) lysine
B) tryptophan
C) histidine
D) tyrosine

Question 54

Serotonin, a neurotransmitter, has a calming effect. Which of the following amino acids is the precursor of serotonin?

A) arginine
B) glutamic acid
C) isoleucine
D) tryptophan

Question 55

Which of the following neurotransmitters is associated with manic-depressive schizophrenia?

A) adrenaline
B) norepinephrine
C) serotonin
D) none of these

Question 56

Which of the following amino acids absorbs UV radiation at 280 nm?

A) arginine
B) alanine
C) leucine
D) tyrosine

Question 57

Which of the following amino acids functions as a hormone?

A) leucine
B) lysine
C) thyroxine
D) tyrosine

Question 58

Which protein contains both hydroxylysine and hydroxyproline?

A) actin
B) collagen
C) fibrinogen
D) hemoglobin

Question 59

From which amino acid is tyrosine usually derived?

A) cysteine
B) phenylalanine
C) tryptophan
D) valine

Question 60

What is the chemical name of serotonin?

A) 5-hydroxyphenylalanine
B) 5-hydroxytryptamine
C) 3-hydroxytyrosine
D) 3-hydroxyvaline

Question 61

How are the dipeptides Ala-Gly and Gly-Ala related to each other?

A) They are the same compound.
B) They have the same properties.
C) They are constitutional isomers.
D) They are mirror images.

Question 62

Which of the following dipeptides is alanylserine?

A)
B)
C)
D)

Question 63

At which pH does a protein have the lowest solubility?

A) at a very low pH
B) at a neutral pH of 7
C) at a very high pH
D) at its isoelectric point

Question 64

How are amino acids primarily linked in a protein?

A) by peptide bonds
B) by hydrogen bonds
C) by ester bonds
D) by ionic bonds

Question 65

Which of the following defines the primary structure of a protein?

A) the geometric arrangement of the backbone atoms of a protein
B) the geometric arrangement of the side chains of a protein
C) the sequence of the amino acids in a protein
D) all of the above

Question 66

Which of the following is true of the atoms in a protein's backbone unit?

A) All of them are in a straight line.
B) All of them are in the same plane.
C) All of them have tetrahedral geometry.
D) None of these are correct.

Question 67

How many different dipeptides can be made from 20 amino acids?

A) 20
B) 40
C) 200
D) 400

Question 68

Which of the following dipeptides is alanylglycine?

A)
B)
C)
D)

Question 69

What is the conformation of the peptide bond that is present between the amino acids in a protein?

A) planar
B) chair
C) bent
D) nonplanar

Question 70

Identify the correct representation of the given tripeptide.

A) Ala-Cys-Asp
B) Ala-Cys-Glu
C) Asp-Cys-Ala
D) Glu-Cys-Ala

Question 71

What is the direction of protein synthesis?

A) from the C-terminus to the N-terminus
B) from the middle toward both the ends
C) from the N-terminus to the C-terminus
D) The direction varies from one protein to another.

Question 72

What is a residue?

A) An amino acid that has been severed from a protein
B) Any individual amino acid in a protein or a polypeptide
C) The portion of a protein that remains after one amino acid has been removed from its C-terminus
D) The portion of a protein that remains after one amino acid has been removed from its N-terminus

Question 73

Identify the correct representation of the given tripeptide.

A) Ala-Cys-Asp
B) Ala-Cys-Glu
C) Asp-Cys-Ala
D) Glu-Cys-Ala

Question 74

How are the two chains of insulin linked?

A) by peptide bonds
B) by ester bonds
C) by hydrogen bonds
D) by disulfide bonds

Question 75

Identify the correct naming convention followed while naming a protein or polypeptide.

A) The convention of naming proteins is different from that of polypeptides.
B) They are named starting from the C-terminus residue to the N-terminus residue.
C) They are named starting from the middle toward both ends.
D) They are named starting from the N-terminus residue to the C-terminus residue.

Question 76

At which pH does a protein have a net positive charge?

A) at its isoelectric point
B) never
C) at the pH above its isoelectric point
D) at the pH below its isoelectric point

Question 77

At which pH does a protein have a net negative charge?

A) at its isoelectric point
B) never
C) at the pH above its isoelectric point
D) at the pH below its isoelectric point

Question 78

Which of the following dipeptides is serylalanine?

A)
B)
C)
D)

Question 79

Which of the following statements is true of the polarity of proteins?

A) All proteins are acidic.
B) All proteins are basic.
C) All proteins are neutral.
D) The polarity of a protein depends on its side chains.

Question 80

Which of the following dipeptides is glycylalanine?

A)
B)
C)
D)