Chapter 5 Practice Problems Flashcards
(15 cards)
When oxygen binds to a heme-containing protein, the two open coordination bonds of Fe2+ are occupied by:
A.) one O2 molecule and one heme atom
B.) two O2 molecules
C.) one O atom and one amino acid atom
D.) one O2 molecule and one amino acid atom
E.) two O atoms
D.) one O2 molecule and one amino acid atom
Which of the following is not correct concerning 2,3-biphosphoglycerate (BPG)?
A.) it is an allosteric modulator
B.) it binds with lower affinity to fetal hemoglobin than to adult hemoglobin
C.) it is normally found associated with the hemoglobin extracted from red blood cells
D.) it increases the affinity of hemoglobin for oxygen
E.) it binds at a distance from the heme groups of hemoglobin
D.) it increases the affinity of hemoglobin for oxygen
Carbon monoxide (CO) is toxic to humans because:
A.) it binds to myoglobin and causes it to denature
B.) it binds to the Fe2+ in hemoglobin and prevents the binding of O2
C.) it binds to the heme portion of the hemoglobin and causes heme to unbind from hemoglobin
D.) it is rapidly converted to toxic CO2
E.) it binds to the globin portion of hemeoglobin and prevents the binding of O2
B.) it binds to the Fe2+ in hemoglobin and prevents the binding of O2
In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as:
A.) random
B.) linear with positive slope
C.) linear with negative slope
D.) sigmoidal
E.) hyperbolic
E.) hyperbolic
The fundamental cause of sickle-cell disease is a change in the structure of:
A.) the heart
B.) capillaries
C.) hemoglobin
D.) blood
E.) red cells
C.) hemoglobin
Which of the following statements about protein-ligand binding is correct?
A.) the Ka is equal to the concentration of ligand when all of the binding sites are occupied
B.) the larger the Ka, the faster the binding
C.) the larger the Ka, the smaller the Kd
D.) the Ka is independent of such conditions as salt concentration and pH
E.) the larger the Ka, the weaker the affinity
C.) the larger the Ka, the smaller the Kd
The interactions of ligands with proteins:
A.) are relatively rare in biological systems
B.) usually result in the inactivation of the proteins
C.) are relatively nonspecific
D.) are usually irreversible
E.) are usually transient
E.) are usually transient
Neuroglobin is a member of the globin family found in neurons. It is a monomeric protein that helps protect the brain from hypoxia (low O2). Identify the correct statement(s) about neuroglobin below
__ and __
A.) It binds O2 with a hyperbolic binding curve.
B.) It binds O2 with a sigmoidal binding curve.
C.) It binds O2 with a higher affinity than hemoglobin.
D.) It binds O2 with a lower affinity than hemoglobin.
A & C
A.) It binds O2 with a hyperbolic binding curve.
C.) It binds O2 with a higher affinity than hemoglobin.
Identify the correct statements regarding the Bohr effect in hemoglobin.
__ and __
A.) The Bohr effect shifts the fractional O2 saturation curve to the right as pH decreases.
B.) The Bohr effect shifts the fractional O2 saturation curve to the right as the pH increases.
C.) The Bohr effect favors O2 release in respiring tissues.
D.) O2 and H+ compete for binding to Hb.
A and C
A.) The Bohr effect shifts the fractional O2 saturation curve to the right as pH decreases.
C.) The Bohr effect favors O2 release in respiring tissues.
During muscle contraction, hydrolysis of ATP results in a change in the:
A.) structure of the myofibrils
B.) conformation of actin
C.) structure of the Z disk
D.) structure of the sarcoplasmic reticulum
E.) conformation of myosin
E.) conformation of myosin
Which of the following generalizations concerning motor proteins is correct?
A.) They convert kinetic energy into rotational energy
B.) They convert kinetic energy into chemical energy
C.) They convert chemical energy into potential energy
D.) They convert chemical energy into kinetic energy
E.) They convert potential energy into chemical energy
D.) They convert chemical energy into kinetic energy
An individual molecular structure within an antigen to which an individual antibody binds is as a(n):
A.) MHC site
B.) Fab region
C.) Fc region
D.) Antigen
E.) epitope
E.) epitope
In hemoglobin, the transition from T state to R state (low to high affinity) is triggered by:
A.) Subunit association
B.) Subunit dissociation
C.) Heme binding
D.) Oxygen binding
E.) Fe2+ binding
D.) Oxygen binding
The amino acid substitution of Val for Glu in Hemoglobin S results in aggregation of the protein because of ____ interactions between molecules.
A.) Ionic
B.) Hydrogen bonding
C.) Hydrophobic
D.) Covalent
E.) Disulfide
C.) Hydrophobic
