EXAM 2 BCH 451 QUESTIONS AND VERIFIED CORRECT
ANSWERS 100% PASS
hemoglobin
binds and transports oxygen from lungs to the tissues inside red blood cells
tetrameric quaternary structure
- four reversible O2 binding pockets each containing heme group
- central cavity contains 6 positively charged side chains; N-terminal amino acid group
of each beta chain forms cationic binding site
4 globins + 4 hemes = __________________
binds to O2 via the chelated iron of the heme group
lower affinity for O2 than myoglobin (see P50)
heme
bioinorganic cofactor that consists of a porphyrin macro-ring composed of four pyrrole
rings
- reduced iron (Fe2+) is held by chelation in the center of the ring
- iron binds equally to all 4 nitrogen atoms
found within hemoglobin and myoglobin
holoprotein
,when required cofactors are bound to a protein it is called a ___________________
apoprotein
when required cofactors are not bound to a protein it is called an _________________
myoglobin
binds O2 in the muscle tissues
structure:
- single polypeptide chain called globin composed of 8 helices
heme group alternately binds oxygen and iron reversibly
- His-64 forms a hydrogen bond with oxygen
- His-93 forms a covalent bond with iron
found in high concentrations in the skeletal and cardiac muscle (gives them their red
color)
binding curve
shows the same information as a pH titration plot:
1. x axis: ligand concentration [H+]
2. y axis: number of H+ bound to A2-
pH titration curve is the same but the x axis is reversed
,1. x axis: pH
2. y axis: number of H+ removed from the A2- binding lattice
P50
the partial pressure of O2 required to acheive 50% occupancy of the binding sites
- myoglobin can only bind one O2, hemoglobin can bind 4
myoglobin _______ = 2.8 torr
hemoglobin ________ = 26 torr
lungs
high partial pressure of oxygen (where hemoglobin binds oxygen)
tissues
low partial pressure of oxygen (where oxygen is released from hemoglobin to bind
cooperative binding
when more than one contact point binds to the substrate, it becomes progressively
more inclined to proceed through the rxn
hemoglobin has a sigmoidal (s-shaped) binding curve that is characteristic
when hemoglobin binds the first O2, binding of subsequent O2 molecules becomes
, easier
mixed cooperativity - positive at low [O2], negative at high [O2]
y axis: fractional saturation of lattice
x axis: PO2 (torr)
2,3-BPG
allosteric effector for hemoglobin
can bind to a regulatory binding site on hemoglobin and stabilize the deoxygenated form
(T state; lower affinity for oxygen)
- when hemoglobin is oxygenated, the beta chains are closer together so the allosteric
binding site is too small to bind _________________
links breathing to our metabolic processes: ____________ is produced during glycolysis
during a phosphorylation rxn requiring ATP
- if there is enough ATP to undergo this rxn, the cell doesn't need more oxygen for the
ETC
- allosteric feedback inhibition
bohr effect
The tendency of certain factors to stablize the hemoglobin in the tense conformation,
thus reducing its affinity for oxygen and enhancing the relase of oxygen to the tissues.
The factors include increased PCO2, increase temperature, increased
ANSWERS 100% PASS
hemoglobin
binds and transports oxygen from lungs to the tissues inside red blood cells
tetrameric quaternary structure
- four reversible O2 binding pockets each containing heme group
- central cavity contains 6 positively charged side chains; N-terminal amino acid group
of each beta chain forms cationic binding site
4 globins + 4 hemes = __________________
binds to O2 via the chelated iron of the heme group
lower affinity for O2 than myoglobin (see P50)
heme
bioinorganic cofactor that consists of a porphyrin macro-ring composed of four pyrrole
rings
- reduced iron (Fe2+) is held by chelation in the center of the ring
- iron binds equally to all 4 nitrogen atoms
found within hemoglobin and myoglobin
holoprotein
,when required cofactors are bound to a protein it is called a ___________________
apoprotein
when required cofactors are not bound to a protein it is called an _________________
myoglobin
binds O2 in the muscle tissues
structure:
- single polypeptide chain called globin composed of 8 helices
heme group alternately binds oxygen and iron reversibly
- His-64 forms a hydrogen bond with oxygen
- His-93 forms a covalent bond with iron
found in high concentrations in the skeletal and cardiac muscle (gives them their red
color)
binding curve
shows the same information as a pH titration plot:
1. x axis: ligand concentration [H+]
2. y axis: number of H+ bound to A2-
pH titration curve is the same but the x axis is reversed
,1. x axis: pH
2. y axis: number of H+ removed from the A2- binding lattice
P50
the partial pressure of O2 required to acheive 50% occupancy of the binding sites
- myoglobin can only bind one O2, hemoglobin can bind 4
myoglobin _______ = 2.8 torr
hemoglobin ________ = 26 torr
lungs
high partial pressure of oxygen (where hemoglobin binds oxygen)
tissues
low partial pressure of oxygen (where oxygen is released from hemoglobin to bind
cooperative binding
when more than one contact point binds to the substrate, it becomes progressively
more inclined to proceed through the rxn
hemoglobin has a sigmoidal (s-shaped) binding curve that is characteristic
when hemoglobin binds the first O2, binding of subsequent O2 molecules becomes
, easier
mixed cooperativity - positive at low [O2], negative at high [O2]
y axis: fractional saturation of lattice
x axis: PO2 (torr)
2,3-BPG
allosteric effector for hemoglobin
can bind to a regulatory binding site on hemoglobin and stabilize the deoxygenated form
(T state; lower affinity for oxygen)
- when hemoglobin is oxygenated, the beta chains are closer together so the allosteric
binding site is too small to bind _________________
links breathing to our metabolic processes: ____________ is produced during glycolysis
during a phosphorylation rxn requiring ATP
- if there is enough ATP to undergo this rxn, the cell doesn't need more oxygen for the
ETC
- allosteric feedback inhibition
bohr effect
The tendency of certain factors to stablize the hemoglobin in the tense conformation,
thus reducing its affinity for oxygen and enhancing the relase of oxygen to the tissues.
The factors include increased PCO2, increase temperature, increased
