Question 1

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 2

It is possible for two different proteins to contain the same number and type of amino acids.

Accepted Answer

A) True 
 B)False

Question 3

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 4

Which protein stores O2 in tissues?

Accepted Answer

A) Keratin 
B) Ferritin 
C) Hemoglobin 
D) Myoglobin

Question 5

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

Accepted Answer

A) True 
 B)False

Question 6

________ proteins are composed of long linear polypeptide chains that are bundled together to form rods or sheets that are insoluble in water and serve structural roles.

Accepted Answer

The answer of ________ proteins are composed of long linear...

Question 7

What is the one-letter abbreviation of arginine?

Accepted Answer

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

Question 8

Which choice is the only amino acid capable of forming a disulfide bond?

Accepted Answer

A) Methionine 
B) Serine 
C) Arginine 
D) Cysteine

Question 9

Based on its name,which compound is an enzyme?

Accepted Answer

A) Glucose 
B) Triosephosphate isomerase 
C) N-acetyl-D-glucosamine 
D) Dihydrofolate

Question 10

What is the charge on a zwitterion?

Accepted Answer

A) Positive 
B) Neutral 
C) Negative 
D) The charge or lack of charge varies depending on the amino acid.

Question 11

Amino acids with an additional COOH group in the side chain are classified as acidic amino acids.

Accepted Answer

A) True 
 B)False

Question 12

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 13

Zwitterions have low melting points and are water-soluble.

Accepted Answer

A) True 
 B)False

Question 14

Amino acids are the building blocks of the body's proteins. Which statement concerning amino acids is false?

Accepted Answer

A) There are approximately 200 standard amino acids that occur naturally in the proteins of the human body. 
B) Except for when R=H,amino acids are chiral molecules. 
C) The amino acids found in human proteins are "alpha" amino acids. 
D) The properties of amino acids and the proteins they compose are determined by the nature of the side chain groups that are present.

Question 15

Trypsin is a digestive enzyme that hydrolyzes peptide bonds only when the carbonyl group in the amide bond comes from Lys or Arg. What fragments result when the peptide Gly-Lys-Arg-Ala-Ala-Arg is hydrolyzed by trypsin?

Accepted Answer

A) Gly,Lys,Arg,Ala-Ala,Arg 
B) Gly-Lys,Arg-Ala-Ala,Arg 
C) Gly-Lys,Arg,Ala-Ala,Arg

Question 16

What is the structure of the dipeptide Ser-Gly?

Accepted Answer

A)   
B)   
C)   
D)

Question 17

The β-pleated sheet forms when two or more peptide chains,called strands,line up side-by-side with the C=O and N-H bonds in the plane of the sheets.

Accepted Answer

A) True 
 B)False

Question 18

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.

Question 19

The pH at which an amino acid exists primarily in its neutral form is called its ________ point.

Accepted Answer

The answer of The pH at which an amino acid...

Question 20

What type of intermolecular forces exist between the side chains of serine and asparagine?

Accepted Answer

A) Electrostatic attraction 
B) London dispersion forces 
C) Hydrogen bond 
D) Disulfide bond

Exam 21: Amino Acids,proteins,and Enzymes

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?

It is possible for two different proteins to contain the same number and type of amino acids.

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

Which protein stores O₂ in tissues?

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

________ proteins are composed of long linear polypeptide chains that are bundled together to form rods or sheets that are insoluble in water and serve structural roles.

What is the one-letter abbreviation of arginine?

Which choice is the only amino acid capable of forming a disulfide bond?

Based on its name,which compound is an enzyme?

What is the charge on a zwitterion?

Amino acids with an additional COOH group in the side chain are classified as acidic amino acids.

What is a zymogen?

Zwitterions have low melting points and are water-soluble.

Amino acids are the building blocks of the body's proteins. Which statement concerning amino acids is false?

Trypsin is a digestive enzyme that hydrolyzes peptide bonds only when the carbonyl group in the amide bond comes from Lys or Arg. What fragments result when the peptide Gly-Lys-Arg-Ala-Ala-Arg is hydrolyzed by trypsin?

What is the structure of the dipeptide Ser-Gly?

The β-pleated sheet forms when two or more peptide chains,called strands,line up side-by-side with the C=O and N-H bonds in the plane of the sheets.

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?

The pH at which an amino acid exists primarily in its neutral form is called its ________ point.

What type of intermolecular forces exist between the side chains of serine and asparagine?