Question 1

A protein has a molecular weight of 5600 daltons; its subunits are about 1960 daltons. There are protein chains per oligomer.

Accepted Answer

A)  4 
B)  3 
C)  2 
D)  1 
E)  Cannot determine from the information given 
A)  4 
B)  3 
C)  2 
D)  1 
E)  Cannot determine from the information given B

Question 2

All amino acids can readily interconvert between the cis and trans forms by rotation about the peptide bond.

Accepted Answer

A) True 
 B)False  False

Question 3

The hydrophobic crevice of globin prevents complete electron transfer to the oxygen so that the electron returns to the iron atom when oxygen dissociates.

Accepted Answer

A) True 
 B)False  True

Question 4

Proline is the least common amino acid in α-helices due to its inability to fully participate in intrahelical hydrogen bonding.

Accepted Answer

A) True 
 B)False

Question 5

The association of hydrophobic side chains in the interior of proteins helps to stabilize helices and pleated sheet domains.

Accepted Answer

A) True 
 B)False

Question 6

How many complete turns are there in an ideal α-helix that contains 15 amino acids and has a pitch of 0.54 nm and a rise of 0.15 nm?

Accepted Answer

A)  1 
B)  4 
C)  8 
D)  59 
A)  1 
B)  4 
C)  8 
D)  59

Question 7

Which demonstrates that the primary structure of a protein determines its tertiary structure?

Accepted Answer

A)  How the disulfide bonds hold it in the correct shape. 
B)  Proteins can refold even when the amino acid sequence is changed. 
C)  Proteins refold when the amino acid sequence is the same as in the native conformation. 
D)  Chaotropic agents cannot denature the native conformation. 
E)  All of the above 
A)  How the disulfide bonds hold it in the correct shape. 
B)  Proteins can refold even when the amino acid sequence is changed. 
C)  Proteins refold when the amino acid sequence is the same as in the native conformation. 
D)  Chaotropic agents cannot denature the native conformation. 
E)  All of the above

Question 8

For each term select the description that best describes its contribution to the structure of collagen. A) Has $ \mathrm{H} $ bonds which help stabilize the protein
B) Makes the protein rigid
C) Required for hydroxylation
D) Forms covalent cross links
E) Allows tightly wound helix formation
-Proline

Accepted Answer

The answer of For each term select the description that...

Question 9

Which statement is false about the heme group?

Accepted Answer

A)  When oxygen binds to heme, the iron ion is oxidized from Fe2+ to Fe3+. 
B)  If exposed to air, a free heme group not associated with hemoglobin) is readily oxidized converting Fe2+ to Fe3+ and can no longer bind oxygen. 
C)  The heme group is tightly, but non-covalently, held in myoglobin molecule. 
D)  The chemical structure of the heme groups in myoglobin and hemoglobin are identical. 
A)  When oxygen binds to heme, the iron ion is oxidized from Fe2+ to Fe3+. 
B)  If exposed to air, a free heme group not associated with hemoglobin) is readily oxidized converting Fe2+ to Fe3+ and can no longer bind oxygen. 
C)  The heme group is tightly, but non-covalently, held in myoglobin molecule. 
D)  The chemical structure of the heme groups in myoglobin and hemoglobin are identical.

Question 10

Part of immunoglobulin molecules can be changed in order to bind to a variety of antigens while the amino acid sequence of another part does not change.

Accepted Answer

A) True 
 B)False

Question 11

Conditions in the tissues which enhance the delivery of oxygen by hemoglobin are the presence of

Accepted Answer

A)  carbon dioxide. 
B)  2,3 BPG. 
C)  protons. 
D)  All of the above 
E)  A and B above 
A)  carbon dioxide. 
B)  2,3 BPG. 
C)  protons. 
D)  All of the above 
E)  A and B above

Question 12

The Tm of a protein is temperature at which it

Accepted Answer

A)  is completely denatured. 
B)  liquifies. 
C)  is half denatured. 
D)  resists denaturation. 
A)  is completely denatured. 
B)  liquifies. 
C)  is half denatured. 
D)  resists denaturation.

Question 13

Hemoglobin is

Accepted Answer

A)  a tetramer of 4 myoglobin proteins. 
B)  a tetramer of four globin chains and one heme prosthetic group. 
C)  a dimer of subunits each with two distinct protein chains alpha and beta). 
D)  a dimer of subunits each with two myoglobin proteins. 
E)  an erythrocyte. 
A)  a tetramer of 4 myoglobin proteins. 
B)  a tetramer of four globin chains and one heme prosthetic group. 
C)  a dimer of subunits each with two distinct protein chains alpha and beta). 
D)  a dimer of subunits each with two myoglobin proteins. 
E)  an erythrocyte.

Question 14

Computers are used to advance the understanding of three dimensional protein structure by

Accepted Answer

A)  determining the specific sequence of amino acids. 
B)  finding repeating subunit patterns. 
C)  calculating atomic positions from X-ray diffraction patterns. 
D)  collimating X-ray beams. 
A)  determining the specific sequence of amino acids. 
B)  finding repeating subunit patterns. 
C)  calculating atomic positions from X-ray diffraction patterns. 
D)  collimating X-ray beams.

Question 15

An ideal α-helix has a pitch of 0.54 nm and a rise of 0.15 nm. What is the length along the helix axis for a segment of an ideal α-helix that contains 30 amino acids?

Accepted Answer

A)  200 nm 
B)  4.50 nm 
C)  16.20 nm 
D)  55.5 nm 
A)  200 nm 
B)  4.50 nm 
C)  16.20 nm 
D)  55.5 nm

Question 16

Which structure below indicates the proper hydrogen-bonding pattern between amino acids in an α-helix? Dashed lines represent the hydrogen bonds.)

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
A)  I 
B)  II 
C)  III 
D)  IV

Question 17

For each term select the description that best describes its contribution to the structure of collagen. A) Has $ \mathrm{H} $ bonds which help stabilize the protein
B) Makes the protein rigid
C) Required for hydroxylation
D) Forms covalent cross links
E) Allows tightly wound helix formation
-Vitamin C

Accepted Answer

The answer of For each term select the description that...

Question 18

NMR is often used for the determination of the of proteins.

Accepted Answer

A)  molecular weight 
B)  isoelectric point 
C)  tertiary structure 
D)  pKa 
A)  molecular weight 
B)  isoelectric point 
C)  tertiary structure 
D)  pKa

Question 19

Once denatured, proteins cannot be renatured or restored to the native state.

Accepted Answer

A) True 
 B)False

Question 20

Chaperones are proteins which prevent incorrect folding of proteins as well as preventing some proteins from aggregating.

Accepted Answer

A) True 
 B)False

Exam 4: Proteins: Three-Dimensional Structure and Function

A protein has a molecular weight of 5600 daltons; its subunits are about 1960 daltons. There are protein chains per oligomer.

All amino acids can readily interconvert between the cis and trans forms by rotation about the peptide bond.

The hydrophobic crevice of globin prevents complete electron transfer to the oxygen so that the electron returns to the iron atom when oxygen dissociates.

Proline is the least common amino acid in α-helices due to its inability to fully participate in intrahelical hydrogen bonding.

The association of hydrophobic side chains in the interior of proteins helps to stabilize helices and pleated sheet domains.

How many complete turns are there in an ideal α-helix that contains 15 amino acids and has a pitch of 0.54 nm and a rise of 0.15 nm?

Which demonstrates that the primary structure of a protein determines its tertiary structure?

Which statement is false about the heme group?

Part of immunoglobulin molecules can be changed in order to bind to a variety of antigens while the amino acid sequence of another part does not change.

Conditions in the tissues which enhance the delivery of oxygen by hemoglobin are the presence of

The Tm of a protein is temperature at which it

Hemoglobin is

Computers are used to advance the understanding of three dimensional protein structure by

An ideal α-helix has a pitch of 0.54 nm and a rise of 0.15 nm. What is the length along the helix axis for a segment of an ideal α-helix that contains 30 amino acids?

Which structure below indicates the proper hydrogen-bonding pattern between amino acids in an α-helix? Dashed lines represent the hydrogen bonds.)

NMR is often used for the determination of the of proteins.

Once denatured, proteins cannot be renatured or restored to the native state.

Chaperones are proteins which prevent incorrect folding of proteins as well as preventing some proteins from aggregating.

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

Filters

The T_mof a protein is temperature at which it