Question 1

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

Accepted Answer

A) True 
 B)False  False

Question 2

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 B

Question 3

The Fischer projection below represents a basic amino acid.

Accepted Answer

A) True 
 B)False  False

Question 4

Since amino acids contain a base (NH2 group)and an acid (COOH),proton transfer from the acid to the base forms a salt called a/an ________,which contains both a positive and a negative charge.

Accepted Answer

Question 5

Which of the following is not of the causes of protein denaturation?

Accepted Answer

A) High temperature 
B) Low temperature 
C) Strong acid 
D) Agitation 
A) High temperature 
B) Low temperature 
C) Strong acid 
D) Agitation

Question 6

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.

Question 7

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 8

Which is not a characteristic of an α-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 9

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 10

What is the structure of the amino acid leucine at pH 12?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 11

________ bonds between cysteine residues are the only covalent bonds that stabilize the tertiary structure of a protein.

Accepted Answer

The answer of ________ bonds between cysteine residues are the...

Question 12

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

Accepted Answer

A) True 
 B)False

Question 13

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

Accepted Answer

A) Structure IV represents the form of Ser present at its isoelectric pH. 
B) Structure III represents the form of Ser present in the basic environment of the intestines. 
C) Structure II represents the form of Ser present in the acidic environment of the stomach. 
D) Structure I represents the zwitterionic form of Ser. 
A) Structure IV represents the form of Ser present at its isoelectric pH. 
B) Structure III represents the form of Ser present in the basic environment of the intestines. 
C) Structure II represents the form of Ser present in the acidic environment of the stomach. 
D) Structure I represents the zwitterionic form of Ser.

Question 14

Amino acids typically exist in nature as neutral molecules with all uncharged atoms.

Accepted Answer

A) True 
 B)False

Question 15

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 16

The lock-and-key model is often used to explain why some enzymes catalyze a wide variety of substrate reactions.

Accepted Answer

A) True 
 B)False

Question 17

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 18

Which Fischer projections represent naturally-occurring amino acids?

Accepted Answer

A) Only structure 1 
B) Only structure 2 
C) Structures 1,2,and 3 
D) Structures 2 and 3 
A) Only structure 1 
B) Only structure 2 
C) Structures 1,2,and 3 
D) Structures 2 and 3

Question 19

Hemoglobin,collagen,and myoglobin are all examples of conjugated proteins.

Accepted Answer

A) True 
 B)False

Question 20

The amino acids aspartic acid and glutamic acid have a +1 net charge at low pH,and a -2 net charge at high pH.

Accepted Answer

A) True 
 B)False

Exam 21: Amino Acids,proteins,and Enzymes

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

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

The Fischer projection below represents a basic amino acid.

Since amino acids contain a base (NH2 group)and an acid (COOH),proton transfer from the acid to the base forms a salt called a/an ________,which contains both a positive and a negative charge.

Which of the following is not of the causes of protein denaturation?

How is a dipeptide formed?

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

Which is not a characteristic of an α-helix?

Which is an example of a cofactor?

What is the structure of the amino acid leucine at pH 12?

________ bonds between cysteine residues are the only covalent bonds that stabilize the tertiary structure of a protein.

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

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

Amino acids typically exist in nature as neutral molecules with all uncharged atoms.

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

The lock-and-key model is often used to explain why some enzymes catalyze a wide variety of substrate reactions.

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

Which Fischer projections represent naturally-occurring amino acids?

Hemoglobin,collagen,and myoglobin are all examples of conjugated proteins.

The amino acids aspartic acid and glutamic acid have a +1 net charge at low pH,and a -2 net charge at high pH.

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

Metabolism and Energy Production

Carbohydrate,lipid,and Protein Metabolism

Filters

Since amino acids contain a base (NH₂ group)and an acid (COOH),proton transfer from the acid to the base forms a salt called a/an ________,which contains both a positive and a negative charge.