Question 1

How many different dipeptides can be formed when one valine reacts with one glycine?

Accepted Answer

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

Question 2

Which is the simplest amino acid?

Accepted Answer

A) serine 
B) glutamine 
C) cysteine 
D) glycine 
A) serine 
B) glutamine 
C) cysteine 
D) glycine

Question 3

The antibiotics penicillin and sulfanilamide, and drugs used to treat high blood pressure and acquired immune deficiency syndrome (AIDS)are classified as coenzymes.

Accepted Answer

A) True 
 B)False

Question 4

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 5

What is the charge on an amino acid at a pH below its pI?

Accepted Answer

A) positive 
B) neutral 
C) negative 
D) The charge or lack of charge varies depending on the amino acid. 
A) positive 
B) neutral 
C) negative 
D) The charge or lack of charge varies depending on the amino acid.

Question 6

What is a zymogen?

Accepted Answer

A) an amino acid with a neutral charge 
B) inactive precursor of an enzyme 
C) a molecule that causes an enzyme to lose activity 
D) a nonprotein organic molecule needed for an enzyme-catalyzed reaction to occur 
A) an amino acid with a neutral charge 
B) inactive precursor of an enzyme 
C) a molecule that causes an enzyme to lose activity 
D) a nonprotein organic molecule needed for an enzyme-catalyzed reaction to occur

Question 7

Tuftsin is a peptide that stimulate and promotes the destruction of tumor cells. Its primary structure is Thr-Lys-Pro-Arg. Which statement is NOT a valid interpretation of its primary structure?

Accepted Answer

A) It is a tetrapeptide. 
B) Threonine is the N-terminal amino acid and arginine is the C-terminal amino acid. 
C) The amino group of arginine is not joined to any other amino acid. 
D) The carboxyl group of lysine is joined to the amino group of proline. 
A) It is a tetrapeptide. 
B) Threonine is the N-terminal amino acid and arginine is the C-terminal amino acid. 
C) The amino group of arginine is not joined to any other amino acid. 
D) The carboxyl group of lysine is joined to the amino group of proline.

Question 8

Which statement is not true?

Accepted Answer

A) A cofactor is always a metal ion needed for an enzyme-catalyzed reaction to occur. 
B) The names of most enzymes end in the suffix -ase. 
C) An enzyme-catalyzed reaction can be 106 to 1012 times faster than a similar uncatalyzed reaction. 
D) Enzymes are proteins that serve as biological catalysts for reactions in all living organisms. 
A) A cofactor is always a metal ion needed for an enzyme-catalyzed reaction to occur. 
B) The names of most enzymes end in the suffix -ase. 
C) An enzyme-catalyzed reaction can be 106 to 1012 times faster than a similar uncatalyzed reaction. 
D) Enzymes are proteins that serve as biological catalysts for reactions in all living organisms.

Question 9

$\alpha$-Keratin in hair is a fibrous protein composed almost exclusively of $\alpha$-helix units that wind together to form a superhelix.

Accepted Answer

A) True 
 B)False

Question 10

The $\beta$-pleated sheet arrangement of a protein is favored by amino acids with small side chains.

Accepted Answer

A) True 
 B)False

Question 11

The $\alpha$-helix and the $\beta$-pleated sheet are examples of the tertiary structure of a protein.

Accepted Answer

A) True 
 B)False

Question 12

The reactant in an enzyme-catalyzed reaction is called a cofactor.

Accepted Answer

A) True 
 B)False

Question 13

Which is an example of a globular protein?

Accepted Answer

A) collagen 
B) $\alpha$-keratin 
C) hemoglobin 
D) amylopectin 
A) collagen 
B) $\alpha$-keratin 
C) hemoglobin 
D) amylopectin

Question 14

A dipeptide contains two amino acids joined together by two amide bonds.

Accepted Answer

A) True 
 B)False

Question 15

The "cartoon" shown is an example of noncompetitive inhibition.

Accepted Answer

A) True 
 B)False

Question 16

The amide bonds in peptides and proteins are called peptide bonds.

Accepted Answer

A) True 
 B)False

Question 17

Serine exists primarily in its neutral form at a pH ~ 6.

Accepted Answer

A) True 
 B)False

Question 18

Zwitterions have low melting points and are water soluble.

Accepted Answer

A) True 
 B)False

Question 19

Hydrogen bonding is possible between the side chains of the amino acids tyrosine and threonine.

Accepted Answer

A) True 
 B)False

Question 20

The peptide leucylphenylalanylvalylvaline is abbreviated as Leu-Phen-Ala-Val-Val.

Accepted Answer

A) True 
 B)False

Exam 21: Amino Acids, Proteins, and Enzymes

How many different dipeptides can be formed when one valine reacts with one glycine?

Which is the simplest amino acid?

The antibiotics penicillin and sulfanilamide, and drugs used to treat high blood pressure and acquired immune deficiency syndrome (AIDS)are classified as coenzymes.

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

What is the charge on an amino acid at a pH below its pI?

What is a zymogen?

Tuftsin is a peptide that stimulate and promotes the destruction of tumor cells. Its primary structure is Thr-Lys-Pro-Arg. Which statement is NOT a valid interpretation of its primary structure?

Which statement is not true?

α\alphaα -Keratin in hair is a fibrous protein composed almost exclusively of α\alphaα -helix units that wind together to form a superhelix.

The β\betaβ -pleated sheet arrangement of a protein is favored by amino acids with small side chains.

The α\alphaα -helix and the β\betaβ -pleated sheet are examples of the tertiary structure of a protein.

The reactant in an enzyme-catalyzed reaction is called a cofactor.

Which is an example of a globular protein?

A dipeptide contains two amino acids joined together by two amide bonds.

The "cartoon" shown is an example of noncompetitive inhibition.

The amide bonds in peptides and proteins are called peptide bonds.

Serine exists primarily in its neutral form at a pH ~ 6.

Zwitterions have low melting points and are water soluble.

Hydrogen bonding is possible between the side chains of the amino acids tyrosine and threonine.

The peptide leucylphenylalanylvalylvaline is abbreviated as Leu-Phen-Ala-Val-Val.

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

$\alpha$ -Keratin in hair is a fibrous protein composed almost exclusively of $\alpha$ -helix units that wind together to form a superhelix.

The $\beta$ -pleated sheet arrangement of a protein is favored by amino acids with small side chains.

The $\alpha$ -helix and the $\beta$ -pleated sheet are examples of the tertiary structure of a protein.