What is the primary component of hemoglobin responsible for oxygen binding?
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The heme group.
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What is the primary component of hemoglobin responsible for oxygen binding?
The heme group.
Where does erythropoiesis occur during the first few weeks of gestation?
In the yolk sac.
What process leads to the formation of red blood cells?
Erythropoiesis.
What is the primary function of hemoglobin?
To transport oxygen from the lungs to the tissues and facilitate carbon dioxide transport back to the lungs.
What is the structure of hemoglobin composed of?
Hemoglobin is composed of four polypeptide chains, each with a heme group that binds oxygen.
What is the normal hemoglobin concentration in packed RBCs?
34 g per 100 mL.
What is the effect of anemia on the hemoglobin-oxygen dissociation curve?
Anemia reduces the plateau of the curve but less significantly than CO.
What percentage of CO2 is transported by binding to the polypeptide chain of hemoglobin?
Approximately 10-15%.
What role do iron ions play in hemoglobin?
Iron ions in the heme groups are essential for oxygen binding.
How does Myoglobin (Mb) release O2?
It releases O2 when O2 levels are very low in the tissues, such as during exercise.
What is the average RBC count for females?
4,700,000 (± 300,000) / mm³.
How is ATP generated in red blood cells?
By glycolysis.
Why does oxygen pass more easily from maternal HbA to fetal HbF?
Because fetal hemoglobin (HbF) has a higher affinity for oxygen.
What is the characteristic of hemoglobin's state changes?
They are dynamic and change according to conditions.
What is formed when hemoglobin binds with CO2?
Carbaminohemoglobin (HbCO2).
What mutation causes sickle cell anemia?
A single nucleotide substitution (A to T) in the codon for amino acid 6.
What enzyme converts 1,3-diphosphoglycerate to 2,3-DPG?
2,3-BPG mutase.
How does the shape of Red Blood Cells facilitate their function?
The biconcave shape increases surface area, making interactions easier and providing flexibility.
Where does the majority of CO2 conversion occur in the body?
In the tissues.
What type of change occurs in the amino acid due to the mutation in sickle cell anemia?
A polar to nonpolar change.
How does local temperature affect hemoglobin's affinity for oxygen?
It can facilitate or release oxygen depending on the temperature.
What are erythrocytes usually devoid of?
Nucleus, mitochondria, Golgi apparatus, ribosomes, and other organelles.
What is the primary function of red blood cells?
To transport oxygen throughout the body.
What can stimulate an increase in RBC counts?
Higher altitudes.
What triggers the shift of hemoglobin from the T state to the R state?
Surrounding conditions, specifically oxygenation.
How does hemoglobin's structure relate to its function?
The quaternary structure allows for cooperative binding of oxygen, enhancing its efficiency in oxygen transport.
What are the thickness measurements of a Red Blood Cell?
Thick rim is 2.5 microns; thin center is 1 micron.
What are the types of globin chains involved in hemoglobin formation?
α, β, γ, δ, and during embryonic life, ζ and ε.
What role does the heme group play in hemoglobin?
It binds to oxygen molecules.
What factors are involved in the allosteric regulation of hemoglobin?
O2, 2,3-DPG, CO2, and H+.
What effects do changes in hemoglobin structure have?
They cause alterations in O2 binding capacity.
Who were the scientists associated with the Bohr Effect?
Bohr C, Hasselbach K, and Krogh A.
What is the significance of HbF's affinity for O2?
It allows the fetus to extract oxygen from maternal blood more effectively.
Can hemoglobin shift between T and R states?
Yes, it shifts according to surrounding conditions.
What is the normal hemoglobin level in blood?
14 - 15 g per 100 mL.
What occurs when hemoglobin becomes protonated?
It forms HHb+.
What effect does hemoglobin have on blood viscosity?
It contributes to viscous blood.
What is the significance of the quaternary structure of hemoglobin?
The quaternary structure allows for cooperative binding of oxygen, enhancing oxygen transport efficiency.
What effect does 2,3-DPG binding have on hemoglobin's affinity for oxygen?
It stabilizes hemoglobin in the T state, thus reducing affinity for O2 and shifting the curve to the right.
What are Thalassemias?
Genetic conditions resulting in reduced production of either alpha or beta globins.
What is the average RBC count for males?
5,200,000 (± 300,000) / mm³.
How does the concentration of CO2 affect hemoglobin's binding to O2?
Higher concentration of CO2 decreases hemoglobin's affinity for O2.
What conditions can cause an increase in RBC production?
Hypoxic conditions.
What role does the placenta play in the Double Bohr effect?
It facilitates the transfer of oxygen from maternal blood to fetal blood.
What compound is formed when carbon monoxide binds to hemoglobin?
Carboxyhemoglobin (COHb).
What is the significance of the quaternary structure of hemoglobin?
It allows hemoglobin to change shape upon oxygen binding, increasing its affinity for additional oxygen molecules.
What is the primary effect of CO binding to hemoglobin?
It reduces the oxygen-carrying capacity of hemoglobin.
How does the binding of CO to hemoglobin affect oxygen delivery?
It impairs oxygen delivery to tissues.
What role do hydrogen ions (H+) play in hemoglobin function?
They help modulate hemoglobin's affinity for oxygen.
How many heme groups are associated with each globin chain in hemoglobin?
Each globin chain is associated with one heme group.
What is the role of iron (Fe2+) in hemoglobin?
Each heme group contains one atom of iron that can bind oxygen.
What is cooperative binding in hemoglobin?
It refers to the change in hemoglobin's affinity for O2 based on the number of heme groups already bound to O2.
Which organs are involved in erythropoiesis during the mid-trimester?
Liver, spleen, and lymph nodes.
What are the two states of hemoglobin?
Tense (T) and Relaxed (R) states.
What is the affinity of carbon monoxide (CO) for the heme group compared to oxygen (O2)?
CO has approximately 250 times higher affinity for the heme group than O2.
What is the deoxygenated state of hemoglobin referred to as?
Tense (T) state.
What is the oxygenated state of hemoglobin referred to as?
Relaxed (R) state.
What percentage of total glycolysis may occur via the alternative pathway that produces 2,3-DPG?
Approximately 20%.
What is the Haldane Effect?
The phenomenon where deoxygenated hemoglobin has a higher affinity for carbon dioxide.
What enzyme converts bicarbonate and H+ into H2O and CO2?
Carbonic anhydrase.
What is HbA2 and its composition?
A small portion (~1-3%) of HbA2 is formed by 2 alpha and 2 delta globins.
What impact does asthma have on oxygen transport?
Asthma can impair oxygen delivery and exchange.
What factors can affect hemoglobin's main function?
Factors that alter Hb affinity for O2, CO2, and 2,3-DPG can affect its ability to transport O2 and assist in acid-base regulation.
How many heme groups are present in one hemoglobin molecule?
Four heme groups.
What are the main structural differences between oxygenated and deoxygenated hemoglobin?
These differences assist in O2 and CO2 transport and pH regulation in the body.
What happens when H+ binds to hemoglobin?
It favors the tense (T) state conformation of hemoglobin.
What triggers the shift of hemoglobin from the tense (T) state to the relaxed (R) state?
Surrounding conditions.
What role do heme groups play in hemoglobin?
Heme groups contain iron, which binds to oxygen molecules.
What role does carbon dioxide play in the Bohr Effect?
Higher levels of carbon dioxide lower pH, enhancing oxygen release from hemoglobin.
What is the relationship between the Bohr Effect and oxygen dissociation?
The Bohr Effect facilitates the dissociation of oxygen from hemoglobin in acidic conditions.
What is the oxygen carrying capacity of hemoglobin?
1.34 mL/g Hgb, or 19 - 20 mL O2 / 100 mL of blood.
What physiological change occurs in individuals adapted to high altitudes?
Increased levels of 2,3-DPG by approximately 50-60% (from 5 mmol/L to 8 mmol/L).
How do the structures of Myoglobin (Mb) and Hemoglobin (Hb) differ?
Myoglobin is a single subunit protein, while Hemoglobin has four subunits.
How many oxygen molecules can one hemoglobin molecule transport?
One hemoglobin molecule can transport 4 oxygen molecules (O2) or 8 oxygen atoms.
What is the lifespan of red blood cells (RBCs)?
Approximately 120 days.
What do reticulocytes retain that supports hemoglobin synthesis?
A small amount of endoplasmic reticulum and mRNA.
Where does erythropoiesis primarily occur in adults?
In the bone marrow.
When does bone marrow become the primary site of RBC production?
In the last month of gestation through adulthood.
What is the Bohr Effect?
The physiological phenomenon where increased carbon dioxide and decreased pH result in hemoglobin releasing more oxygen.
What is the diameter of a Red Blood Cell?
7.8 microns.
Where does carbon monoxide bind in hemoglobin?
To the heme group.
What is the average volume of a Red Blood Cell?
90 - 95 micrometers³.
What is the structure of the β subunits of hemoglobin (HbA)?
It consists of α-helices shown as cylinders, with segments marked by colored digits: red for α-helices and green for loops.
What type of dissociation curve does Myoglobin (Mb) exhibit for O2?
A hyperbolic dissociation curve.
How can heart failure affect oxygen delivery?
It may reduce O2 delivery to tissues, leading to acidosis and lung congestion.
What is Sickle cell anemia characterized by?
The presence of Sickle Hb (HbS), which is detrimental for O2 transport.
What is the relationship between O2 and CO2 binding to hemoglobin?
O2 displaces CO2 from Hb, while CO2 and H+ displace O2 from Hb.
How does the binding of one O2 molecule affect the binding of subsequent O2 molecules?
Each O2 molecule that binds facilitates the binding of the next O2 molecule.
What is the Double Bohr effect?
It refers to the enhanced transfer of oxygen from maternal hemoglobin (HbA) to fetal hemoglobin (HbF) due to HbF's higher affinity for O2.
What is the primary site of erythropoiesis in adults?
Bone marrow.
How does carbon monoxide (CO) affect the hemoglobin-oxygen dissociation curve?
CO shifts the curve down and leftward, reducing the plateau.
What is the primary function of hemoglobin (Hb)?
To transport oxygen from the lungs to the tissues and facilitate carbon dioxide transport back to the lungs.
What are the components of hemoglobin?
Hemoglobin is composed of four polypeptide chains, each containing a heme group that binds oxygen.
How does hemoglobin change when it binds to oxygen?
Hemoglobin undergoes a conformational change that increases its affinity for oxygen.
What is the molecular weight of Hemoglobin A (HbA)?
64,458.
What is marked with a red ellipse in the structure of hemoglobin?
Helix D, which is the dominant difference between β and α subunits.
What happens to CO2 in the lungs?
It is exhaled, with a small amount binding to hemoglobin.
What is the predominant form of hemoglobin in the fetus?
Fetal hemoglobin (HbF), formed by 2 alpha and 2 gamma globins.
How can amino acid substitutions affect hemoglobin?
They can lead to reduced binding of 2,3-DPG and higher affinity for oxygen.
How does 2,3-DPG modulate Hb-O2 affinity?
2,3-DPG binds to Hb, stabilizing the T state and reducing O2 affinity.
What is the relationship between hemoglobin's affinity for O2 and acidity (pH)?
The affinity is inversely related to acidity (pH).
What are the two states of hemoglobin?
Tense (T) state and Relaxed (R) state.
What are the main differences between myoglobin and hemoglobin?
Myoglobin is primarily for oxygen storage, while hemoglobin is for oxygen transport.
What is the shape of Red Blood Cells (RBCs)?
Biconcave discs.
What happens to hemoglobin when CO2 and H+ levels increase?
Hemoglobin undergoes conformational changes favoring the tense (T) state.
What is 2,3-DPG and how is it formed?
2,3-DPG is formed during the conversion of glucose to lactate via an alternative pathway to the main glycolytic pathway.
What is the primary function of Myoglobin (Mb)?
To serve as a reservoir of O2 for exercising muscles.
How does carbon dioxide affect hemoglobin's state?
It contributes to favoring either the T or R state.
Which has a higher affinity for O2, Myoglobin (Mb) or Hemoglobin (Hb)?
Myoglobin (Mb) has a higher affinity for O2.
What organelles are typically absent in mature red blood cells?
Nucleus and other organelles.
What is the average lifespan of red blood cells (RBCs)?
Approximately 120 days.
What happens to hemoglobin's affinity for O2 as more heme groups bind O2?
Hemoglobin's affinity for O2 increases.
What is the deoxygenated state of hemoglobin referred to as?
Tense (T) state.
How does acidity affect oxygen delivery in the Bohr Effect?
Increased acidity promotes oxygen dissociation from hemoglobin.
What are the two states of hemoglobin?
Tense (T) and Relaxed (R) states.
What factors modulate hemoglobin's affinity for oxygen?
Carbon dioxide (CO2), hydrogen ions (H+), 2,3-diphosphoglycerate (2,3-DPG or 2,3-BPG), and local temperature.
What is the primary form in which CO2 is transported in the blood?
As bicarbonate (HCO3-) and H+.
What amino acid change occurs in sickle cell anemia?
Glutamic acid (GAG) is converted to valine (GTG).
What happens to 2,3-DPG after it is formed?
It is converted to 3-phosphoglycerate by 2,3-DPG phosphatase.
What role does Myoglobin (Mb) play in intracellular O2 transport?
It helps transport O2 from the plasma membrane to mitochondria.
From what did Myoglobin (Mb) and Hemoglobin (Hb) evolve?
They evolved from a common ancestral gene.
What is MetHb and its significance?
Methemoglobin (MetHb) has increased levels of heme with Fe3+ and cannot bind O2.
What is the significance of hemoglobin being saturated in low affinity?
It indicates that hemoglobin can hold onto O2 more effectively when it is fully saturated.
What is the oxygenated state of hemoglobin referred to as?
Relaxed (R) state.
What is the normal range for hematocrit?
40 - 45% (slightly lower in women).
What does a leftward shift in the hemoglobin-oxygen dissociation curve indicate?
Increased affinity of hemoglobin for oxygen.
What is the significance of the plateau in the hemoglobin-oxygen dissociation curve?
It indicates the saturation of hemoglobin with oxygen.
What is the predominant form of hemoglobin in adults?
Hemoglobin A (HbA), which consists of 2 α and 2 β chains.
What stabilizes the heme group in hemoglobin?
The distal (E7H) and proximal (F8H) histidines.
What is the normal adult hemoglobin structure?
Formed by 2 alpha and 2 beta subunits (HbA).
What is the significance of genetic variants in hemoglobin?
There are over 1,000 naturally occurring Hb variants that can alter Hb affinity for O2 or its modulators.
What role do cytoskeleton proteins play in Red Blood Cells?
They confer large deformation capacity, allowing RBCs to squeeze through capillaries.
How does the Bohr effect influence hemoglobin's affinity for oxygen?
It decreases hemoglobin's affinity for O2.
What happens to hemoglobin in homozygous individuals ('SS') when exposed to low oxygen?
It forms elongated crystals, leading to vascular occlusion and hemolysis.
What is the significance of 2,3-diphosphoglycerate (2,3-DPG) in hemoglobin function?
It influences the balance between the T and R states of hemoglobin.
What color represents the α-helices in the hemoglobin structure?
Red.
What color represents the loops in the hemoglobin structure?
Green.
What happens to the Hb-O2 dissociation curve due to the Bohr effect?
It shifts to the right.
Where does 2,3-DPG bind in hemoglobin?
To the central charged cavity of deoxyhemoglobin.
What advantage does the heterozygote condition provide in populations?
It offers some protection against malaria.
How does heavy smoking affect hemoglobin function?
Increases carbon monoxide inhalation and may lead to lung emphysema.
What effect does high O2 have in the lungs regarding CO2 and H+?
High O2 displaces CO2 and H+, reducing available binding sites for 2,3-DPG as Hb shifts to the R state.
Why does HbF have a higher affinity for oxygen?
Because it has low affinity for 2,3-DPG, as gamma globins don’t form the binding site for it.
What state must iron be in for hemoglobin to bind oxygen?
Iron must be in the ferrous (Fe2+) state to bind oxygen; ferric (Fe3+) cannot bind.
What happens in the tissues when CO2 and H+ levels are high?
High CO2 and H+ (lower pH) displace O2 and increase available binding sites for 2,3-DPG as Hb shifts to the T state.
