Question 1

In sickle-cell anemia,the negatively charged glutamic acid residue is replaced by the neutral amino acid ____________.

Accepted Answer

A) tyrosine 
B) lysine 
C) valine 
D) adenosine 
E) glycine

Question 2

While the binding of O2 to myoglobin as a function of pO2 is described by a simple __________ curve,the binding to hemoglobin is described by a more complex ______ curve.

Accepted Answer

A) sigmoidal;hyperbolic 
B) hyperbolic;sigmoidal 
C) exponential;hyperbolic 
D) sigmoidal;bell-shaped 
E) hyperbolic;concave

Question 3

Which of the statements about muscle contraction is not true?

Accepted Answer

A) During muscle contraction the sarcomere becomes shorter. 
B) During muscle contraction the I band becomes shorter. 
C) During muscle contraction the H zone becomes shorter. 
D) During muscle contraction the A band becomes shorter 
E) During muscle contraction the distance between the Z disk and the M disk becomes shorter.

Question 4

Matching

-Hemoglobin's subunits bind oxygen in a ______ manner.

Accepted Answer

A)  positively cooperative 
B)  cyanosis 
C)  His E7 
D)  decrease 
E)  R
F) hydrogen bonds
G) increase
H) symmetry
I) His F8
J) ion pairs
K) T
L) hemolytic anemia
M) sequencial

Question 5

Why is the decreased affinity of fetal hemoglobin for BPG advantageous?

Accepted Answer

A) With fewer BPG molecules bound there are more heme residues available for O2 binding. 
B) Decreased BPG binding biases the fetal hemoglobin toward the R state. 
C) More free BPG is available to bind to adult hemoglobin,resulting in a shift to the R state. 
D) BPG is available to bind to fetal myoglobin,helping to release O2 in fetal muscle tissue. 
E) none of the above

Question 6

During muscle contraction

Accepted Answer

A) myosin pulls actin filaments toward the M disk. 
B) myosin pushes actin filaments toward the Z disk. 
C) actin pulls myosin toward the Z disk. 
D) actin pushes myosin toward the M disk. 
E) All of the answers above are correct.

Question 7

The reaction of carbonic anhydrase catalyzes

Accepted Answer

A) the formation of carbamates with the concomitant release of protons. 
B) the hydration of bicarbonate,resulting in the formation of carbonic acid. 
C) the reduction of carbon dioxide with the concomitant consumption of protons. 
D) the hydration of carbon dioxide,forming bicarbonate and protons. 
E) the hydrolysis of carbamates with the concomitant consumption of protons.

Question 8

If the gene for myoglobin is "knocked out" in mice,the mice:

Accepted Answer

A) have larger lungs. 
B) respire extremely rapidly. 
C) have dark brown muscle tissue. 
D) appear normal,with lighter colored muscle tissue. 
E) have their growth stunted.

Question 9

Which of the following is not a ligand to the porphyrin ring Fe(II) ion in oxymyoglobin?

Accepted Answer

A) His E7 
B) His F8 
C) Nitrogen atoms in the porphyrin ring 
D) Oxygen 
E) all are ligands

Question 10

Which gas does not bind to the porphyrin ring Fe(II)ion in myoglobin?

Accepted Answer

A) NO 
B) CO 
C) CO2 
D) O2 
E) H2S

Question 11

Hemoglobin's p50 value is about ______ as great as myoglobin's p50 value.

Accepted Answer

A) one-tenth 
B) half 
C) twice 
D) ten times 
E) twenty times

Question 12

During muscle contraction myosin heads

Accepted Answer

A) walk along thick filaments toward the M disk. 
B) walk along thick filaments toward the Z disk. 
C) walk along thin filaments toward the M disk. 
D) walk along the thin filaments toward the H zone. 
E) walk along the thin filaments toward the Z disk.

Question 13

What is the type of symmetry that relates the protomers in hemoglobin with respect to each other?

Accepted Answer

A) C2 
B) C4 
C) D2 
D) D4 
E) Tetrahedral symmetry

Question 14

How many antigen-binding sites are present on an IgM molecule?

Accepted Answer

A) 2 
B) 4 
C) 10 
D) 16 
E) 25

Question 15

Humoral immunity is mediated by soluble molecules.Which cell type produces the soluble molecules that carry out the humoral immunity?

Accepted Answer

A) T cells 
B) B cells 
C) macrophages 
D) neutrophils 
E) monocytes

Question 16

Which statement about antigen-binding sites in antibodies is false?

Accepted Answer

A) An antigen-binding site on an IgG is formed by the amino-terminal ~110 amino acids of a light chain and the amino terminal ~110 amino acids of a heavy chain. 
B) An antigen-binding site on an IgG is formed by the variable region of a light chain and the variable region of a heavy chain. 
C) The antigen-binding site is composed of two Ig folds. 
D) Antigen-binding specificity is determined by the sequences of the hypervariable sequences in both the light chain and the heavy chain. 
E) Antigen binding specificity is determined exclusively by the sequences in the carboxy-terminal ~110 amino acids in the light chain and the heavy chain.

Question 17

What is the primary physiological function of myoglobin in most mammals?

Accepted Answer

The answer of What is the primary physiological function of...

Question 18

The Bohr effect refers to

Accepted Answer

A) the decrease in affinity of Hb for O2 when the pH goes down 
B) the decrease in affinity of Hb for O2 when the pH goes up 
C) the increase in the affinity of Hb for O2 when the O2 concentration goes up 
D) the decrease in affinity of Hb for O2 when the BPG concentration goes up 
E) the decrease in affinity of Hb for O2 when the BPG concentration goes down

Question 19

The graph below shows the O₂-binding curves for myoglobin (Mb)and hemoglobin (Hb). a.Label the two curves (indicate which one represents Mb and which one represents Hb). b.Use the graph to determine the K_d of myoglobin for O₂ (show your approach). c.What is the difference between myoglobin and hemoglobin that cause the O₂-binding curves to so be different? d.Why is it important that hemoglobin has these particular O₂-binding characteristics?

Accepted Answer

The answer of The graph below shows the O₂-binding curves...

Question 20

Max Perutz's investigation of the structure of hemoglobin primarily utilized_____.

Accepted Answer

A) X-ray crystallography 
B) NMR spectroscopy 
C) genomics 
D) mass spectrometry 
E) genetic engineering

Exam 7: Protein Function Part I: Myoglobin and Hemoglobin