E. Two proteins, myoglobin and hemoglobin, are compared. (Questions 20-30)
20._____
Which characteristics are shared by these two proteins?
a)
They both are globular proteins containing the common amino acids,
porphyrin, and iron.
b)
They both have closely related primary, secondary, tertiary, and
quaternary structures.
c)
They both are composed of multiple subunits each of which contains a
heme prosthetic group.
d)
They both have similar molecular weights and bind one oxygen molecule
per protein molecule.
21._____
Which is a property of protein tertiary structure?
a)
Tertiary structures usually contain hydrocarbon R-groups in the interior of
the protein where they can form hydrogen bonds.
b)
Tertiary structures usually contain hydroxyl R-groups on the exterior of
the protein where they can favorably interact with water.
c)
A protein’s tertiary structure can be predicted if the amino acid sequence is
known by performing the Edman degradation.
d)
A protein’s tertiary structure can be maintained by covalent salt bridges and
non-covalent disulfide bridges.
22._____
Which is a characteristic of protein quaternary structure?
a)
A protein composed of identical subunits has quaternary structure but not
tertiary structure.
b) A protein composed of non-identical subunits contains two polypeptide
chains with opposite charges.
c)
The quaternary structure of a multimeric protein always includes covalent
crosslinks between the subunits.
d)
The quaternary structure of a multimeric protein always depends upon the
primary structure of the subunits.
23._____
Which is a property of tertiary structure and quaternary structure?
a)
Both structures are stabilized by numerous covalent hydrophobic and
hydrophilic interactions.
b)
Both structures have specific shapes that depend upon the amino acid
sequence of the protein.
c)
Both structures form so that polar amino acid R-groups are found mainly in
the interior of the protein.
d)
Both structures must contain multiple
α
-helices and
β
-pleated sheets
connected by turns.