Question 1

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

Accepted Answer

A) True 
 B)False

Question 2

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

Accepted Answer

A) True 
 B)False

Question 3

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.

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.

Question 5

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

Accepted Answer

A) True 
 B)False

Question 6

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

Accepted Answer

A) True 
 B)False

Question 7

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

Question 8

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

Accepted Answer

A) True 
 B)False

Question 9

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

Accepted Answer

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

Question 10

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.

Question 11

Which is the simplest amino acid?

Accepted Answer

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

Question 12

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

Accepted Answer

A) True 
 B)False

Question 13

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.

Question 14

$\alpha$-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 15

Zwitterions have low melting points and are water soluble.

Accepted Answer

A) True 
 B)False

Question 16

Which is an example of a globular protein?

Accepted Answer

A)  collagen
B)   α\alphaα -keratin
C)  hemoglobin
D)  amylopectin

Question 17

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

Accepted Answer

A) True 
 B)False

Question 18

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 19

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

Accepted Answer

A) True 
 B)False

Question 20

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

Accepted Answer

A) True 
 B)False

Exam 21: Amino Acids, Proteins, and Enzymes

Which is the simplest amino acid?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which is an example of a globular protein?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is a zymogen?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which statement is not true?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Zwitterions have low melting points and are water soluble.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

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

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

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