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Questions and Answers
What is the difference between hemoglobin and myoglobin?
What is the difference between hemoglobin and myoglobin?
Hemoglobin has a lower affinity for oxygen than myoglobin. Hemoglobin is also a tetrameric protein, while myoglobin is only a monomer.
Myoglobin has higher affinity for oxygen than hemoglobin?
Myoglobin has higher affinity for oxygen than hemoglobin?
True (A)
What is the main benefit of hemoglobin having multiple subunits?
What is the main benefit of hemoglobin having multiple subunits?
The multiple subunits of hemoglobin enable cooperative binding of oxygen. This means that the binding of one oxygen molecule to a subunit increases the affinity of the other subunits for oxygen, allowing for efficient transport of oxygen from the lungs to the tissues.
What are the two types of globin proteins in adult hemoglobin?
What are the two types of globin proteins in adult hemoglobin?
What type of proteins exhibit cooperative behavior?
What type of proteins exhibit cooperative behavior?
What are the two models that explain how cooperative proteins perform their function?
What are the two models that explain how cooperative proteins perform their function?
The sequential model explains how the binding of a ligand to one subunit makes binding easier for the next subunit.
The sequential model explains how the binding of a ligand to one subunit makes binding easier for the next subunit.
The concerted model explains that all subunits of a protein bind to a ligand at the same time.
The concerted model explains that all subunits of a protein bind to a ligand at the same time.
What is the ligand for hemoglobin?
What is the ligand for hemoglobin?
The saturation curve of hemoglobin binding to oxygen has a sigmoidal shape.
The saturation curve of hemoglobin binding to oxygen has a sigmoidal shape.
What is the P50 of hemoglobin?
What is the P50 of hemoglobin?
In contrast to hemoglobin, myoglobin has a low P50.
In contrast to hemoglobin, myoglobin has a low P50.
What happens to hemoglobin when the oxygen pressure is less than P50?
What happens to hemoglobin when the oxygen pressure is less than P50?
Hemoglobin becomes saturated with oxygen at high oxygen pressures, such as those found in the lungs.
Hemoglobin becomes saturated with oxygen at high oxygen pressures, such as those found in the lungs.
What happens to hemoglobin when it releases oxygen in tissues?
What happens to hemoglobin when it releases oxygen in tissues?
How do the chains of hemoglobin interact with each other?
How do the chains of hemoglobin interact with each other?
Hydrophobic amino acids are only present in the interior of protein chains.
Hydrophobic amino acids are only present in the interior of protein chains.
Electrostatic interactions and hydrogen bonds also exist between the different chains of hemoglobin.
Electrostatic interactions and hydrogen bonds also exist between the different chains of hemoglobin.
The binding of one dimer to another dimer in hemoglobin is permanent.
The binding of one dimer to another dimer in hemoglobin is permanent.
Hemoglobin is an allosteric protein.
Hemoglobin is an allosteric protein.
What are the two forms of hemoglobin?
What are the two forms of hemoglobin?
The T-state of hemoglobin has a high affinity for oxygen.
The T-state of hemoglobin has a high affinity for oxygen.
The R-state of hemoglobin has 500 times higher affinity for oxygen than the T-state.
The R-state of hemoglobin has 500 times higher affinity for oxygen than the T-state.
What causes the conformational changes in hemoglobin that switch it between T and R states?
What causes the conformational changes in hemoglobin that switch it between T and R states?
Any cooperative protein is considered an allosteric protein.
Any cooperative protein is considered an allosteric protein.
What is different about the structure of heme when it is free of oxygen compared to when it is bound to oxygen?
What is different about the structure of heme when it is free of oxygen compared to when it is bound to oxygen?
What happens to proximal histidine (F8) when oxygen binds to heme?
What happens to proximal histidine (F8) when oxygen binds to heme?
The movement of proximal histidine triggers changes in the tertiary structure of individual hemoglobin subunits.
The movement of proximal histidine triggers changes in the tertiary structure of individual hemoglobin subunits.
Movement of the helix in myoglobin does not affect the function of myoglobin.
Movement of the helix in myoglobin does not affect the function of myoglobin.
Breakage of the electrostatic bonds in oxygen-free hemoglobin chains contributes to the switch from the T-state to the R-state.
Breakage of the electrostatic bonds in oxygen-free hemoglobin chains contributes to the switch from the T-state to the R-state.
Cooperative binding occurs as each oxygen molecule that binds causes a decrease in the affinity of hemoglobin to bind more oxygen.
Cooperative binding occurs as each oxygen molecule that binds causes a decrease in the affinity of hemoglobin to bind more oxygen.
Explain the protective mechanism that makes a sudden drop in pulmonary capillary oxygen tension not affect hemoglobin saturation.
Explain the protective mechanism that makes a sudden drop in pulmonary capillary oxygen tension not affect hemoglobin saturation.
High altitudes can affect the saturation of hemoglobin.
High altitudes can affect the saturation of hemoglobin.
What is the effect of pH on hemoglobin?
What is the effect of pH on hemoglobin?
The Bohr effect describes the effect of CO2 on hemoglobin?
The Bohr effect describes the effect of CO2 on hemoglobin?
How does CO2 directly affect hemoglobin?
How does CO2 directly affect hemoglobin?
There is a space in the core of hemoglobin where all the subunits meet because of their positively charged amino acids.
There is a space in the core of hemoglobin where all the subunits meet because of their positively charged amino acids.
Which amino acids are mainly responsible for creating a positive charge in the core of hemoglobin?
Which amino acids are mainly responsible for creating a positive charge in the core of hemoglobin?
What is the role of bisphosphoglycerate (BPG) in hemoglobin?
What is the role of bisphosphoglycerate (BPG) in hemoglobin?
Fetal hemoglobin has a lower affinity for oxygen than adult hemoglobin.
Fetal hemoglobin has a lower affinity for oxygen than adult hemoglobin.
Why does fetal hemoglobin have a higher affinity for oxygen than adult hemoglobin?
Why does fetal hemoglobin have a higher affinity for oxygen than adult hemoglobin?
BPG is a product of the glycolysis pathway.
BPG is a product of the glycolysis pathway.
What is the main reason why it is important to use freshly donated blood for transfusions?
What is the main reason why it is important to use freshly donated blood for transfusions?
Flashcards
Hemoglobin
Hemoglobin
A protein that binds oxygen and transports it in the blood.
Myoglobin
Myoglobin
A protein that binds oxygen and stores it in muscles.
Allostery
Allostery
The ability of a protein to change its shape upon binding a ligand.
T-state (Taut)
T-state (Taut)
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R-state (Relaxed)
R-state (Relaxed)
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P50
P50
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Cooperative Binding
Cooperative Binding
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Bohr Effect
Bohr Effect
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2,3-Bisphosphoglycerate (BPG)
2,3-Bisphosphoglycerate (BPG)
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Fetal Hemoglobin
Fetal Hemoglobin
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Allostery
Allostery
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Hemoglobin Conformational Change
Hemoglobin Conformational Change
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Hemoglobin's Oxygen Transport Function
Hemoglobin's Oxygen Transport Function
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Hemoglobin Subunit Interactions
Hemoglobin Subunit Interactions
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Sigmoidal Saturation Curve
Sigmoidal Saturation Curve
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Oxygen Transport
Oxygen Transport
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Oxygen Release
Oxygen Release
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Carbon Dioxide Binding
Carbon Dioxide Binding
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Carbamate Formation
Carbamate Formation
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BPG Binding
BPG Binding
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Oxygen Affinity Difference
Oxygen Affinity Difference
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Oxygen Binding
Oxygen Binding
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Hemoglobin's Oxygen Saturation Capacity
Hemoglobin's Oxygen Saturation Capacity
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Hemoglobin Quaternary Structure
Hemoglobin Quaternary Structure
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Hydrophobic Interactions in Hemoglobin
Hydrophobic Interactions in Hemoglobin
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Electrostatic and Hydrogen Bonds in Hemoglobin
Electrostatic and Hydrogen Bonds in Hemoglobin
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Alpha and Beta Subunits
Alpha and Beta Subunits
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Oxygen Dissociation
Oxygen Dissociation
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Hemoglobin's Protective Mechanism
Hemoglobin's Protective Mechanism
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Hemoglobin's Physiological Function
Hemoglobin's Physiological Function
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Study Notes
Hemoglobin
- Hemoglobin is a protein that transports oxygen in the blood
- It's a tetramer (four protein chains: two alpha and two beta)
- It has a sigmoidal oxygen binding curve, meaning its oxygen affinity changes with the partial pressure of oxygen
- This cooperative binding allows hemoglobin to pick up oxygen in the lungs (high partial pressure) and release it in the tissues (low partial pressure)
- Hemoglobin's affinity for oxygen is lower than myoglobin's, facilitating oxygen delivery to tissues.
Hemoglobin Structure-Function Relationship
- Hemoglobin's structure allows it to change its affinity for oxygen, enabling efficient oxygen transport between lungs and tissues. This mechanism involves subunits interacting, changing the overall shape and affinity.
- Hemoglobin has a lower affinity for oxygen compared to myoglobin, crucial for its role in releasing oxygen in tissues.
- This difference in affinity arises from the quaternary structure, where subunits facilitate oxygen loading and unloading.
Cooperative Behavior
- Hemoglobin exhibits cooperative binding, meaning the binding of one oxygen molecule increases the binding affinity of the other subunits for oxygen.
- Two models explain this behavior:
- Sequential model: The binding of oxygen to one subunit facilitates oxygen binding to other subunits.
- Concerted model: All subunits change conformation simultaneously when oxygen binds.
P50
- P50 is the partial pressure of oxygen at which hemoglobin is 50% saturated.
- Myoglobin has a lower P50 than hemoglobin.
- Hemoglobin's P50 is approximately 26 mmHg, indicating its optimal function in delivering oxygen to tissues.
- This parameter reflects the protein's oxygen-binding properties.
Hemoglobin Allostery
- Hemoglobin is an allosteric protein, meaning the binding of one molecule (like oxygen) affects the binding of other molecules (like other ligands).
- The T-state (tense state) has a low oxygen affinity, while the R-state (relaxed state) has a high oxygen affinity.
- Oxygen binding induces a change from the T to the R state, enhancing oxygen release to tissues.
- Factors like pH and carbon dioxide concentration influence hemoglobin's oxygen affinity, and affect its structural changes and thus efficiency.
Other Factors Affecting Hemoglobin
- pH affects hemoglobin's oxygen affinity, decreasing in acidic conditions. This facilitates oxygen release, especially in tissues with high metabolic activity.
- Carbon dioxide (CO2) also reduces hemoglobin's oxygen affinity to increase CO2 removal
- 2,3-bisphosphoglycerate (BPG) binds to hemoglobin, lowering its oxygen affinity in tissues. Therefore, its affinity decreases in exercising tissues, as well as tissues that have high metabolism or other energy demands.
- Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin to facilitate efficient oxygen transfer from the mother to the fetus.
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