Chapter 5
Section 5.1
1)
The heme prosthetic group:
a. is found only in myoglobin and hemoglobin.
b. consists of protoporphyrin and iron (II) ion.
c. is the reason for cooperative binding of O2 by hemoglobin.
d. is the reason for cooperative binding of O2 by myoglobin.
2) Myoglobin:
a. has quaternary structure.
b. has no Hill coefficient.
c. binds O2 with lower affinity than hemoglobin.
d. consists mostly of  helices.
3) Protein A has a Ka = 6.0 M–1 for binding ligand L, and protein B has a Kd = 4.0 M for binding of
L.
a. The Ka of protein B for L is 0.25 M–1.
b. Protein B binds L with higher affinity.
c. Protein A is half-saturated with L when [L] = 6.0 M–1.
d. When [L] = 1 M, Y = 0.17 for protein A.
4) Which statement is FALSE?
a. Hemoglobin can be considered a dimer of  dimers.
b. 2,3-bisphosphoglycerate decreases the affinity of hemoglobin for O2.
c. Hemoglobin transports CO2.
d. O2 binding to myoglobin is allosteric but not cooperative.
5) Regarding the models of cooperativity:
a. the concerted model is based on the T state and the sequential on the R state.
b. the concerted model and the sequential model are mutually exclusive.
c. T state is low affinity and R state is high affinity.
d. These models, strictly speaking, only apply to tetramers.
6) When using the Hill equation:
a. log Kd must be converted to log P50
b. it is possible to observe negative cooperativity.
c. it cannot be applied to noncooperative binding.
d. it will never be 1 for a multisubunit protein.
7) The Bohr effect:
a. applies to both myoglobin and hemoglobin.
b. relates [H+] to [CO2].
c. explains through the Bohr model of the atom why Fe2+ will bind O2 in heme but Fe3+
will not.
d. contributes to binding of O2 by hemoglobin in lungs and release of O2 from
hemoglobin in tissues.
Section 5.2
8) The molecular structure for which an individual antibody or T-cell receptor is specific is known
as:
a. its target.
b. an epitope.
c. an immune response.
d. an immunoglobulin fold.
9) Which description is associated with immunoglobulin G?
a. consists of one heavy and one light chain
b. consists of two Fc fragments and two Fab fragments
c. most abundant immunoglobulin
d. important in the allergic response
10) Immunoglubulins:
a. bind tightly to their antigens.
b. form four classes of antibodies.
c. bind antigens with a 1:1 stoichiometry.
d. are produced and secreted by macrophages.
11) Antibodies are NOT used in:
a. column chromatography.
b. ELISA assays.
c. Northern blot assays.
d. Western blot assays.
Section 5.3
12) Which of the major proteins involved in muscle contraction hydrolyzes ATP?
a. titin
b. Na+-K+ ATPase
c. myosin
d. actin
13) _____ are NOT a feature of muscle fibers.
a. Myofibrils
b. Helicases
c. M-lines
d. Sarcomeres
14) What prevents binding of myosin to actin?
a. troponin C
b. troponin I
c. troponin A
d. troponin M
15) What metal ion is critical in muscle contraction?
a. Na+
b. K+
c. Mg2+
d. Ca2+
16) Leghemoglobin is an oxygen-binding protein in root nodules that contain bacteria that fix
atmospheric nitrogen. Which statement is TRUE if leghemoglobin is like myoglobin and not
hemoglobin?
a. There are four oxygen-binding sites.
b. The O2-binding curve is hyperbolic.
c. There is cooperative oxygen binding.
d. The O2-binding curve is sigmoidal.
e. O2 binding changes the heme configuration from T to R.
17) What is the actual, significant effect of 2,3-bisphosphoglycerate on oxygen binding by
hemoglobin?
a. There is an increase in Kd for oxygen in peripheral tissues.
b. A higher concentration of oxygen can bind at high altitudes compared to low altitudes.
c. The affinity of hemoglobin for oxygen in peripheral tissues increases at high altitudes.
d. Heme further decreases affinity for both CO2 and H+ in lungs, allowing more O2 to bind.
e. It has no effect on O2 affinity, but it forces heme into the R-state.
18) Which biochemical principle is NOT true of immunoglobulins as examples of protein structure
and function?
a. Disulfide linkages strengthen the quaternary protein structure.
b. Because the antigen-binding domain has high affinity, there is no observed induced fit..
c. Amino acid chain flexibility and bond rotation permit optimal epitope binding.
d. There are two specific and identical binding sites with high affinity on the same molecule.
e. There is 100% sequence homology between the two antigen binding sites.
19) How does myosin generate force for muscle contraction?
a. Titan regulates the length of the thick and thin filaments.
b. Hydrolysis of ATP promotes a conformational change in myosin.
c. Ca2+ release from the sarcoplasmic reticulum promotes tropomyosin binding to the thick
filament, inducing a conformational change in myosin.
d. The extended coiled coil tail of myosin wraps around actin.
e. Myosin binds to the Z-disk to bring the M-line closer to the A-band.
Ch5
1) b
2) d
3) a
4) d
5) c
6) b
7) d
8) b
9) c
10) a
11) c
12) c
13) b
14) b
15) d
16) b
17) a
18) b
19) b