Final Review Cards/Questions Flashcards
What is the primary function of myoglobin (Mb)?
Stores and transports oxygen in muscles
Myoglobin provides oxygen for metabolic processes to convert/produce energy.
How does myoglobin respond to muscle activation?
Desaturates upon muscle activation
This process increases diffusion from capillaries to the cytoplasm.
What is the role of hemoglobin (Hb)?
Transports oxygen from the lungs to tissue
Hemoglobin also transports carbon dioxide from tissue to lungs.
What is the affinity of hemoglobin for oxygen and carbon dioxide?
High affinity for oxygen; low affinity for carbon dioxide
In venous circulation, hemoglobin has a high affinity for carbon dioxide.
What type of bonds are primarily found in single bonds?
Sigma bonds
Sigma bonds are formed by the head-on overlap of atomic orbitals.
What is the oxidation state of iron in heme?
Either Fe2+ or Fe3+
Iron’s oxidation state is crucial for its function in binding oxygen.
What are ligands?
Electron-rich species that coordinate to metal ions
Ligands help stabilize charge and solubilize metal ions.
What structure do iron complexes typically form?
Stable octahedral complexes
This is based on the hybridization of the metal center.
What are porphyrins?
Heterocyclic macrocycles composed of four modified pyrrole subunits
Porphyrins are highly conjugated aromatic compounds found in mammals, plants, and bacteria.
What is the structure of protoporphyrin IX?
Contains heme
Protoporphyrin IX is crucial for the function of hemoproteins.
What is an apoprotein?
Unbound protein that is inactive
Apoproteins are necessary for heme to become water soluble.
What is the quaternary structure of hemoglobin?
Tetrameric structure
Fetal hemoglobin has a different structure with higher affinity than adult hemoglobin.
True or False: Carbon monoxide (CO) binds better than oxygen (O2) to heme.
True
CO binds to the same site as O2 but with a much higher affinity.
Fill in the blank: Myoglobin is a _______ heme protein.
monomeric
This indicates that myoglobin consists of a single polypeptide chain.
What is the significance of the coordination sites in iron?
Contains six coordination sites
These sites are based on the hybridization of the metal center and are important for binding ligands.
What is the main role of heme complexes?
Enhance water solubility of heme
Heme complexes are fairly insoluble on their own.
What is the term for the protein that carries oxygen in the blood?
hemoglobin
What type of curve does hemoglobin exhibit in its oxygen binding?
Sigmoidal curve
True or False: Hemoglobin has a higher affinity for O2 when it is in a relaxed state.
t
Fill in the blank: Hemoglobin exhibits _______ cooperation in oxygen binding.
cooperative
What effect does 2,3-Bisphosphoglycerate (BPG) have on hemoglobin’s affinity for oxygen?
It decreases affinity
What is meant by a leftward shift in the oxygen dissociation curve?
Increased affinity for the ligand
What state of hemoglobin is associated with higher oxygen binding?
Relaxed state
What is the role of competitive inhibitors in relation to hemoglobin and oxygen?
Compete with O2 but help maintain hemoglobin’s structure
True or False: Increasing O2 pressure will decrease the binding of CO to hemoglobin.
t
What is the impact of CO2 on hemoglobin’s oxygen binding?
It can promote the release of O2
Fill in the blank: Hemoglobin has _______ affinity for unbound heme.
increased
What happens to hemoglobin’s oxygen affinity when it is in a bound state?
It has a lower affinity for O2
What is the term for the protein that carries oxygen in the blood?
hemoglobin
What type of curve does hemoglobin exhibit in its oxygen binding?
Sigmoidal curve
True or False: Hemoglobin has a higher affinity for O2 when it is in a relaxed state.
t
Fill in the blank: Hemoglobin exhibits _______ cooperation in oxygen binding.
cooperative
What effect does 2,3-Bisphosphoglycerate (BPG) have on hemoglobin’s affinity for oxygen?
It decreases affinity
What is meant by a leftward shift in the oxygen dissociation curve?
Increased affinity for the ligand
What state of hemoglobin is associated with higher oxygen binding?
Relaxed state
What is the role of competitive inhibitors in relation to hemoglobin and oxygen?
Compete with O2 but help maintain hemoglobin’s structure
True or False: Increasing O2 pressure will decrease the binding of CO to hemoglobin.
t
What is the impact of CO2 on hemoglobin’s oxygen binding?
It can promote the release of O2
Fill in the blank: Hemoglobin has _______ affinity for unbound heme.
increased
What happens to hemoglobin’s oxygen affinity when it is in a bound state?
It has a lower affinity for O2
Primary function of myoglobin?
Store and transport oxygen into muscles
What oxidation states can iron exist in heme proteins?
Fe2+(ferrous) and Fe3+(ferric)
Hybridization of iron in heme proteins?
sp3d2
How nmany coordination sites does iron have in heme proteins?
6
What type of structure is formed when all ligands are bound to iron in heme proteins?
Octahedral
Term for an unbound protein that is inactive?
apoprotein
Amino acid residue that binds to the fifth coordination site of iron in heme proteins?
Histidine
Structural difference between hemoglobin and myoglobin?
Myoglobin is monomeric and hemoglobin is a tetrameric
What level of protein structure is represented by a single myoglobin unit?
Tertiary
What level of protein structure is represented by hemoglobin?
Quaternary
What is the hill coefficient for hemoglobin?
2.7
Which state of hemoglobin is known as the tense state?
T State
What is the main difference between fetal and adult hemoglobin?
fetal hemoglobin has gamma subunits instead of beta. (Both have Alpha)
Why does fetal hemoglobin have a higher affinity for oxygen compared to adult hemoglobin?
Because it has more alpha subunits
What percentage of CO2 is transported as dissolved gas in blood plasma?
0.1
What is the effect of increasing temp on oxygen binding to hemoglobin?
Increases oxygen dissociation
What is formed when CO2 binds to the N-terminal group of hemoglobin?
Carbamate
How many times more strongly does carbon monoxide bind to hemoglobin compared to oxygen?
200-300 times
What happens to oxygen affinity when blood pH decreases?
Decreases
What is the main reason hydroxide cannot deprotonate water?
Water is the conjugate acid of hydroxide
What must be true for hydroxide to deprotonate a compound?
The pKa must be below 16
What determines if a compound is an aniline?
The NH2 group MUST be attached to a BENZENE ring
To be an H-Bond acceptor, N or O must have what?
A lone pair of electrons
