Deck 22: Proteins

Question 1

Which of the following amino acids is not optically active?

A) alanine
B) glycine
C) tryptophan
D) None of these, they are all optically active.

Answer 1

B

Question 2

Which of the following is not a fibrous protein?

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

Answer 2

D

Question 3

What is the minimum number of carbon atoms in an α-amino acid?

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

Answer 3

B

Question 4

Approximately how many different proteins are found in the human body?

A) 900
B) 9000
C) 100,000
D) 1,000,000

Question 5

Proteins are associated with which of the following functions?

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

Question 6

Which of the following is a structural protein?

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

Question 7

How many different amino acids are commonly found in proteins?

A) 10
B) 20
C) 200
D) 1000

Question 8

In which of the following is the amino nitrogen also part of the side chain?

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

Question 9

Which of the following is a protein associated the storage of iron?

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

Question 10

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

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

Question 11

Approximately how many different proteins are found in a typical cell?

A) 900
B) 9000
C) 100,000
D) 1,000,000

Question 12

Which of the following side chains are hydrophobic?

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

Question 13

Although all biological molecules are important, which type of molecule is considered the most important?

A) amino acids
B) carbohydrates
C) lipids
D) proteins

Question 14

Which of the following proteins is a hormone?

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

Question 15

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

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

Question 16

What is the most important property of the R groups of the amino acids?

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

Question 17

Which of the following is a protein associated with the movement of muscles?

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

Question 18

Which of the following side chains are hydrophobic?

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

Question 19

Which functional group is involved in linking together the amino acids of proteins?

A) amine
B) anhydride
C) carbonyl
D) carboxyl

Question 20

Which of the following side chains are hydrophilic?

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

Question 21

In which of the following do both amino acids have a polar but neutral side chain?

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

Question 22

In which of the following do both amino acids contain a sulfur atom?

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

Question 23

Which of the following amino acids has the highest pI?

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

Question 24

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

A) their formula weights
B) the polarity of the side chains
C) the presence of nitrogen atoms
D) their existence as zwitterions

Question 25

In which of the following do both amino acids have a nonpolar side chain?

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

Question 26

Which of the following is true about zwitterions?

A) They are positively charged.
B) They are negatively charged.
C) They are electrically neutral.
D) The charge depends on the zwitterion.

Question 27

Which of the following amino acids has the lowest pI?

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

Question 28

What is the approximate pI of most amino acids?

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

Question 29

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) We cannot predict its charge.

Question 30

Which of the following is true of all α-amino acids?

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

Question 31

In which of the following do both amino acids have a basic side chain?

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

Question 32

What type of chemical reaction is involved in the formation of disulfide bonds from thiols?

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

Question 33

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

A) The isoelectric points of all amino acids are the same.
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 the above are true.

Question 34

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

A) They exist in un-ionized form at high pH.
B) They exist in un-ionized form at low pH.
C) They exist at un-ionized form only at the isoelectric point.
D) They do not exist in unionized form at any pH.

Question 35

What determines the characteristics of an amino acid?

A) its molecular weight
B) the identity of its side chain
C) both a and b
D) neither a nor b

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) We cannot predict its charge.

Question 37

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

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

Question 38

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

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

Question 39

Which of the following amino acids is easily dimerized?

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

Question 40

Which of the following contains a disulfide bond?

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

Question 41

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

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

Question 42

How many amino acids have an amide side chain?

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

Question 43

Which of the following amino acids functions as a hormone?

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

Question 44

From which amino acid is tyrosine normally derived?

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

Question 45

Which amino acids are precursors of norepinephrine and epinephrine?

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

Question 46

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

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

Question 47

Which of the following amino acids will exist as a -2 ion at very high pH?

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

Question 48

Which of the following amino acids will exist as a + 2 ion at very low pH?

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

Question 49

Serotonin is formed from which amino acid?

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

Question 50

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

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

Question 51

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

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

Question 52

Which of the following amino acids will exist as a -2 ion at very low pH?

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

Question 53

What type of chemical reaction is involved in the conversion of disulfide bonds to thiols?

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

Question 54

How many amino acids have acidic side chains?

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

Question 55

Neurotransmitters known as catecholamines are formed from which amino acid?

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

Question 56

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

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

Question 57

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

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

Question 58

Which protein contains hydroxylysine and hydroxyproline?

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

Question 59

How many amino acids have basic side chains?

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

Question 60

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

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

Question 61

When will a protein have a net positive charge?

A) always
B) never
C) when the pH is above its isoelectric point
D) when the pH is below its isoelectric point

Question 62

Which of the following describes the atomic makeup of the backbone unit of a protein?

A) 2 carbon atoms, 2 nitrogen atoms, 2 oxygen atoms
B) 3 carbon atoms, 2 nitrogen atoms, 2 oxygen atoms, 1 hydrogen atom
C) 3 carbon atoms, 1 nitrogen atom, 1 oxygen atom, 1 hydrogen atom
D) 3 carbon atoms, 2 nitrogen atoms, 2 oxygen atoms, 2 hydrogen atoms

Question 63

Which of the following is true of proteins?

A) All proteins are acidic.
B) All proteins are basic.
C) All proteins are neutral.
D) The acid/base properties of a protein depend on the identity of its side chains.

Question 64

How many dipeptides can be made using the 20 standard amino acids?

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

Question 65

When will a protein have the lowest solubility?

A) when the pH is very low
B) when the pH = 7
C) when the pH is very high
D) at its isoelectric point

Question 66

What is a residue?

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

Question 67

How is the tripeptide shown designated?

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

Question 68

What is the relationship between Ala−Gly and Gly−Ala?

A) They are the same substance.
B) They are allotropes.
C) They are isomers.
D) They are mirror images.

Question 69

Using the 20 standard amino acids how many dipeptides containing two different amino acids can be made?

A) 20
B) 39
C) 40
D) 380

Question 70

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

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

Question 71

Which of the following defines the primary structure of proteins?

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

Question 72

Which of the following is alanylglycine?

A)
B)
C)
D)

Question 73

When will a protein have a net negative charge?

A) always
B) never
C) when the pH is above its isoelectric point
D) when the pH is below its isoelectric point

Question 74

How is the tripeptide designated?

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

Question 75

When naming a protein or polypeptide which of the following is true?

A) The convention for proteins is different from that for polypeptides.
B) They are named from the C-terminus to the N-terminus.
C) They are named from the middle towards the two ends.
D) They are named from the N-terminus to the C-terminus.

Question 76

Which of the following is glycylalanine?

A)
B)
C)
D)

Question 77

Protein synthesis proceeds in which direction?

A) from the C-terminus to the N-terminus
B) from the middle towards the two ends
C) from the N-terminus to the C-terminus
D) the direction varies from one protein to another

Question 78

Which of the following is serylalanine?

A)
B)
C)
D)

Question 79

Which of the following is alanylserine?

A)
B)
C)
D)

Question 80

How many atoms form the backbone of the repeat unit of a protein?

A) 2
B) 4
C) 6
D) 8