Question 1

Consider the following forms of the amino acid valine (Val). Which statement concerning these structures is false?

Accepted Answer

A) Structure I represents the form of Val present in blood at physiological pH. 
B) Structure II represents the form of Val present in the basic environment of the intestines. 
C) Structure III represents the form of Val present in the acidic environment of the stomach. 
D) Structure IV represents the zwitterions of Val. 
A) Structure I represents the form of Val present in blood at physiological pH. 
B) Structure II represents the form of Val present in the basic environment of the intestines. 
C) Structure III represents the form of Val present in the acidic environment of the stomach. 
D) Structure IV represents the zwitterions of Val.

Question 2

Which protein stores iron in the liver?

Accepted Answer

A) ferritin 
B) keratin 
C) myoglobin 
D) collagen 
A) ferritin 
B) keratin 
C) myoglobin 
D) collagen

Question 3

What is the one-letter abbreviation of arginine?

Accepted Answer

A) A 
B) R 
C) P 
D) G 
A) A 
B) R 
C) P 
D) G

Question 4

The term protein is usually reserved for polymers of more than _____ amino acids.

Accepted Answer

A) 10 
B) 40 
C) 200 
D) 1000 
A) 10 
B) 40 
C) 200 
D) 1000

Question 5

There are _____ amino acids that occur naturally in proteins.

Accepted Answer

The answer of There are _____ amino acids that occur...

Question 6

What is the strongest type of interaction between the side chains of an isoleucine amino acid and a phenylalanine amino acid in a protein?

Accepted Answer

A) hydrogen bonding 
B) London dispersion forces 
C) disulfide bond 
D) electrostatic interactions 
A) hydrogen bonding 
B) London dispersion forces 
C) disulfide bond 
D) electrostatic interactions

Question 7

Humans can synthesize only twenty of the amino acids needed for proteins.

Accepted Answer

A) True 
 B)False

Question 8

What is the particular sequence of amino acids of a protein that are joined together by peptide bonds called?

Accepted Answer

A) the primary structure of a protein 
B) the secondary structure of a protein 
C) the tertiary structure of a protein 
D) the quaternary structure of a protein 
A) the primary structure of a protein 
B) the secondary structure of a protein 
C) the tertiary structure of a protein 
D) the quaternary structure of a protein

Question 9

About one half of the 223 amino acid residues in the enzyme trypsin are hydrophobic. Where in the tertiary structure of this globular protein are these residues most likely to be found?

Accepted Answer

A) At the N-terminal end of the peptide chain. 
B) At the C-terminal end of the peptide chain. 
C) On the exterior surface of the folded protein. 
D) In the interior of the folded protein. 
A) At the N-terminal end of the peptide chain. 
B) At the C-terminal end of the peptide chain. 
C) On the exterior surface of the folded protein. 
D) In the interior of the folded protein.

Question 10

Which is an example of a cofactor?

Accepted Answer

A) lactose 
B) lactose dehydrogenase 
C) NAD+ (nicotinamide adenine dinucleotide) 
D) tryptophan 
A) lactose 
B) lactose dehydrogenase 
C) NAD+ (nicotinamide adenine dinucleotide) 
D) tryptophan

Question 11

Which statement about oxytocin and vasopressin is not true?

Accepted Answer

A) Oxytocin and vasopressin each contain nine amino acids. 
B) Oxytocin and vasopressin each contain cysteine on both sides of a disulfide bond. 
C) Oxytocin and vasopressin each contain a single disulfide bond. 
D) Oxytocin and vasopressin each contain cysteine as the C-terminal amino acid. 
A) Oxytocin and vasopressin each contain nine amino acids. 
B) Oxytocin and vasopressin each contain cysteine on both sides of a disulfide bond. 
C) Oxytocin and vasopressin each contain a single disulfide bond. 
D) Oxytocin and vasopressin each contain cysteine as the C-terminal amino acid.

Question 12

Which is not a characteristic of an $\alpha$-helix?

Accepted Answer

A) The N-H and C=O bonds point along the axis of the helix in opposite directions. 
B) The R groups of the amino acids extend inward toward the core of the helix. 
C) There are 3.6 amino acids in each turn of the helix. 
D) The C=O group of one amino acid is hydrogen bonded to an N-H group four amino acid residues farther along the chain. 
A) The N-H and C=O bonds point along the axis of the helix in opposite directions. 
B) The R groups of the amino acids extend inward toward the core of the helix. 
C) There are 3.6 amino acids in each turn of the helix. 
D) The C=O group of one amino acid is hydrogen bonded to an N-H group four amino acid residues farther along the chain.

Question 13

A diet of rice and tofu provides all essential amino acids.

Accepted Answer

A) True 
 B)False

Question 14

The Fischer projection below represents a basic amino acid.

Accepted Answer

A) True 
 B)False

Question 15

The side chain of which amino acid can form hydrogen bonds with asparagine?

Accepted Answer

A) glycine 
B) valine 
C) tyrosine 
D) alanine 
A) glycine 
B) valine 
C) tyrosine 
D) alanine

Question 16

All amino acids have at least one chirality center.

Accepted Answer

A) True 
 B)False

Question 17

What is the function of myosin in the human body?

Accepted Answer

A) as connective tissue found in tendons, bone, cartilage, and blood vessels 
B) control muscle contractions 
C) stores iron in the liver 
D) controls blood glucose levels 
A) as connective tissue found in tendons, bone, cartilage, and blood vessels 
B) control muscle contractions 
C) stores iron in the liver 
D) controls blood glucose levels

Question 18

Which amino acid is a basic amino acid?

Accepted Answer

A) serine 
B) arginine 
C) cysteine 
D) alanine 
A) serine 
B) arginine 
C) cysteine 
D) alanine

Question 19

How many different tripeptides can be formed when one isoleucine, one alanine, and one glycine react?

Accepted Answer

A) 3 
B) 6 
C) 18 
D) 27 
A) 3 
B) 6 
C) 18 
D) 27

Question 20

How is a dipeptide formed?

Accepted Answer

A) The -NH3+ group of one amino acid forms an amide bond with the -NH3+ group of another amino acid and the elements of H2 are removed. 
B) The -NH3+ group of one amino acid forms an amide bond with the carboxylate (-COO-)of another amino acid, and the elements of H2O are removed. 
C) The carboxylate (-COO-)group of one amino acid forms an amide bond with the carboxylate (-COO-)of another amino acid, and the elements of O2 are removed. 
D) The carboxylate (-COO-)group of one amino acid forms an amide bond the -NH3+ group of another amino acid, and the elements of H2 are removed. 
A) The -NH3+ group of one amino acid forms an amide bond with the -NH3+ group of another amino acid and the elements of H2 are removed. 
B) The -NH3+ group of one amino acid forms an amide bond with the carboxylate (-COO-)of another amino acid, and the elements of H2O are removed. 
C) The carboxylate (-COO-)group of one amino acid forms an amide bond with the carboxylate (-COO-)of another amino acid, and the elements of O2 are removed. 
D) The carboxylate (-COO-)group of one amino acid forms an amide bond the -NH3+ group of another amino acid, and the elements of H2 are removed.

Exam 21: Amino Acids, Proteins, and Enzymes

Consider the following forms of the amino acid valine (Val). Which statement concerning these structures is false?

Which protein stores iron in the liver?

What is the one-letter abbreviation of arginine?

The term protein is usually reserved for polymers of more than _____ amino acids.

There are _____ amino acids that occur naturally in proteins.

What is the strongest type of interaction between the side chains of an isoleucine amino acid and a phenylalanine amino acid in a protein?

Humans can synthesize only twenty of the amino acids needed for proteins.

What is the particular sequence of amino acids of a protein that are joined together by peptide bonds called?

About one half of the 223 amino acid residues in the enzyme trypsin are hydrophobic. Where in the tertiary structure of this globular protein are these residues most likely to be found?

Which is an example of a cofactor?

Which statement about oxytocin and vasopressin is not true?

Which is not a characteristic of an α\alphaα -helix?

A diet of rice and tofu provides all essential amino acids.

The Fischer projection below represents a basic amino acid.

The side chain of which amino acid can form hydrogen bonds with asparagine?

All amino acids have at least one chirality center.

What is the function of myosin in the human body?

Which amino acid is a basic amino acid?

How many different tripeptides can be formed when one isoleucine, one alanine, and one glycine react?

How is a dipeptide formed?

Matter and Measurement

Atoms and the Periodic Table

Ionic Compounds

Covalent Compounds

Chemical Reactions

Energy Changes, Reaction Rates, and Equilibrium

Gases, Liquids, and Solids

Solutions

Acids and Bases

Nuclear Chemistry

Introduction to Organic Molecules and Functional Groups

Alkanes

Unsaturated Hydrocarbons

Organic Compounds That Contain Oxygen, Halogen, or Sulfur

The Three-Dimensional Shape of Molecules

Aldehydes and Ketones

Carboxylic Acids, Esters, and Amides

Amines and Neurotransmitters

Lipids

Carbohydrates

Nucleic Acids and Protein Synthesis

Digestion and the Conversion of Food Into Energy

Carbohydrate, Lipid, and Protein Metabolism

Filters

Which is not a characteristic of an $\alpha$ -helix?