Bio Mod 3 Quiz

25 July 2022
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question
Which statement about hemoglobin binding to carbon monoxide (CO) is true? Select one: a. Hb binds to CO with a higher affinity than oxygen and stabilizes the R state. b. Hb binds to CO with a higher affinity than oxygen and stabilizes the T state. c. Hb binds to CO with a lower affinity than oxygen and stabilizes the R state. d. Hb binds to CO with a lower affinity than oxygen and stabilizes the T state.
answer
Hb binds to CO with a higher affinity than oxygen and stabilizes the R state. Correct! CO has a higher affinity for hemoglobin than oxygen. The binding of CO stabilizes the R state of hemoglobin.
question
When hemoglobin changes from T to R, it has ________ affinity for oxygen. Select one: a. low b. high c. zero d. none of these are correct
answer
high Correct! The R state has a higher affinity for oxygen than the T state.
question
When hemoglobin changes from R to T, it has _______________ affinity for oxygen. Select one: a. low b. high c. none of these are correct d. zero
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low Correct! The T state has a lower affinity for oxygen than the R state.
question
Cooperativity refers to _____. Select one: a. hemoglobin structural changes that increase its affinity for oxygen. b. The ability of hemoglobin to supply the RBC with oxygen for ATP production c. The increased affinity for oxygen that myoglobin has when oxygen concentration is low d. the exchange of oxygen that happens in the placenta between maternal and fetal blood
answer
hemoglobin structural changes that increase its affinity for oxygen. Correct! The four subunits of hemoglobin, along with the heme groups, communicate or "cooperate" with each other to increase hemoglobin's affinity for oxygen. When oxygen binds to the iron atom in a heme group, the heme changes from a bent to a planar state. The change in the heme shape also "tugs" on the protein chain holding the heme group, causing a conformational shift in the protein subunit. Once one subunit has undergone the conformational shift, it influences the conformations of the neighboring subunits such that oxygen binding occurs more easily.
question
When the oxygen concentration is high, the heme shape is _____________. When the oxygen concentration is low, the heme shape is ______________shape. Select one: bent (non-planar), bent (non-planar) bent (non-planar) , planar planar, planar planar, bent (non-planar)
answer
planar, bent (non-planar) Correct! When oxygen concentration is high, the oxygen binds to iron which pulls the iron and brings heme into a planar position. When oxygen is low, the iron is deoxygenated and the heme is then bent.
question
The Bohr effect is a relationship between hemoglobin's oxygen binding behavior in conjunction with the pH of the surroundings. When the pH is low, hemoglobin has _____________ affinity for oxygen and ________ oxygen. Select one: a. low, releases b. low, binds c. high, binds d. high, releases
answer
low, releases Low pH induces the T state which decreases hemoglobin affinity for oxygen; hemoglobin releases oxygen .
question
Bohr effect is a relationship between hemoglobin's oxygen binding behavior in conjunction with the pH of the surroundings. When the pH is high, hemoglobin has _____________ affinity for oxygen and ________ oxygen. Select one: high, binds high, releases low, binds low, releases
answer
high, binds Correct! High pH favors the R state of hemoglobin and stimulates the binding of oxygen (increases oxygen affinity).
question
Relative to the lungs, the pH in the peripheral tissues is _______ because __________________. Select one: a. lower, carbonic anhydrase sequesters protons (H+). b. lower, the CO2 generated by metabolism is converted to bicarbonate, which releases protons (H+). c. lower, the concentration of oxygen decreases. d. higher, the concentration of CO2 decreases
answer
lower, the CO2 generated by metabolism is converted to bicarbonate, which releases protons (H+). Correct. The pH in peripheral tissues is lower compared to the lungs because the CO2generated metabolism is converted to bicarbonate, which releases protons (H+).
question
The Bohr effect is a relationship between hemoglobin's oxygen binding behavior in conjunction with the pH of the surroundings. When the H+ ion concentration increases, the pH of the solution _________________. Select one: decreases changes only if the oxygen concentration increases does not change increases
answer
decreases Correct! pH is a measure of H+ ion concentration. Since the number calculated for pH is the negative of a base 10 logarithm, the more H+ ions present in solution, the lower the pH.
question
Myoglobin stores oxygen, whereas hemoglobin transports oxygen. Which one of the following statements is true? Select one: a. Myoglobin has exactly one-quarter of the affinity for oxygen because it has only one subunit b. Hemoglobin has a higher affinity for oxygen compared to myoglobin c. Hemoglobin and myoglobin both have the same affinity for oxygen d. Myoglobin has a higher affinity for oxygen compared to hemoglobin
answer
Myoglobin has a higher affinity for oxygen compared to hemoglobin Correct! At lower oxygen concentrations, a much higher fraction of myoglobin would be saturated with oxygen compared to hemoglobin.
question
Hemoglobin is an oxygen transport protein, whereas myoglobin is an oxygen storage protein. They exhibit different binding curves when plotted on a graph with total partial pressure of the oxygen (x-axis) plotted against the percentage saturation of hemoglobin (y-axis). Which pattern of binding curves do these proteins exhibit? Select one: a. Both have a hyperbolic binding curve b. Hemoglobin has a sigmoidal curve whereas the myoglobin has a hyperbolic curve c. Myoglobin has a sigmoidal curve whereas the hemoglobin has a hyperbolic curve d. Both have a sigmoidal binding curve
answer
Hemoglobin has a sigmoidal curve whereas the myoglobin has a hyperbolic curve Correct! Myoglobin has a much higher affinity for oxygen with percent saturation increasing rapidly in low oxygen concentrations; this is demonstrated by a hyperbolic curve. Hemoglobin initially binds to oxygen at a slower rate at low oxygen concentrations, demonstrated by a sigmoidal curve.
question
Hemoglobin and myoglobin proteins bind to molecular oxygen. However, the protein part of the hemoglobin does not bind directly to the oxygen. Instead, a specific atom helps bind the oxygen. Which one of the following will help hemoglobin directly bind to the oxygen? Select one: a. Carbon monoxide b. Histidine c. Heme d. Iron
answer
Iron Correct! Iron is the atom that binds directly with oxygen.
question
Based on the graph- 50% of Hemoglobin is saturated with oxygen at approximately _________ torr, whereas ______________% of myoglobin is saturated with oxygen at the same concentration. 40, 90% 50, 50% 28, 90% 24, 50%
answer
28, 90% Correct! Use the dotted line to find 50% (fraction saturation on the y-axis) and then read the oxygen concentration (torr) on the x-axis.
question
Which one of the following statements is true about the graph? The R state is the prevalent form of hemoglobin at low pH. The R state is favored by the low pH and induces the binding of oxygen The T state of hemoglobin is favored by low pH and induces the release of oxygen The T state of hemoglobin is favored by high pH and induces the release of oxygen
answer
The T state of hemoglobin is favored by low pH and induces the release of oxygen The T state is favored by low pH and induces hemoglobin to release oxygen. As the pH declines (curve shifts to the right), the percent saturation also decreases. Notice that at pH 7.2 (low), the percent saturation is about 20 % when oxygen concentration is 20. However, when pH is 7.6 under the same conditions, the percentage saturation is about 40%.
question
Which one of the following statements is true about the graph? The oxygen binding curve shifts to the right when the pH of the surrounding tissues is low and majority of the hemoglobin is in the T state. The oxygen binding curve shifts to the right when the pH of the surrounding tissues is high and the majority of the hemoglobin is in the R state. The oxygen binding curve shifts to the left when pH of the surrounding tissue is high and the majority of the hemoglobin is in the T state. The oxygen binding curve shifts to the left when pH of the surrounding tissue is low the majority of the hemoglobin is in the T state.
answer
The oxygen binding curve shifts to the right when the pH of the surrounding tissues is low and majority of the hemoglobin is in the T state. Notice how that the curves on the graph move (or shift) to the right as the pH declines. Lower pH is associated with hemoglobins T state.
question
Which one of the following statements is true about the following graph? a. Low concentration of the carbon dioxide and high concentration of the protons (H+ ions) in the tissue will shift the graph to the left b. High concentration of the oxygen and low concentration of the protons (H+ ions) in the tissues will shift the graph to the left c. High concentration of the carbon dioxide and high concentration of the protons (H+ ions) in the tissue will shift the graph to the right d. High concentration of the oxygen and low concentration of the protons (H+ ions) in the tissues will shift the graph to the right
answer
High concentration of the carbon dioxide and high concentration of the protons (H+ ions) in the tissue will shift the graph to the right Oxygen does not affect the concentration of protons (H+ ions) in the tissues and does not affect pH.
question
The symptoms of sickle cell anemia are primarily because red blood cells are misshaped. This is due to ____. Select one: a. a mutation in the beta hemoglobin gene which leads to insertion of glutamate into the hydrophobic patches on oxygenated hemoglobin. b. a mutation in the alpha hemoglobin gene which leads to the insertion of valine into the hydrophobic patches on oxygenated hemoglobin. c. a mutation in the beta hemoglobin gene which leads to the insertion of valine into the hydrophobic patches on deoxygenated hemoglobin. d. a mutation in the alpha hemoglobin gene which leads to the insertion of valine into the hydrophobic patches on deoxygenated hemoglobin.
answer
a mutation in the beta hemoglobin gene which leads to the insertion of valine into the hydrophobic patches on deoxygenated hemoglobin. Sickle cell anemia is a mutation in the beta subunit of hemoglobin.
question
Relative to the peripheral tissues, the pH in the lungs is _______ because __________________. Select one: a. higher, the protons (H+) that were combined with hemoglobin quickly bind to bicarbonate (HCO3-) to form CO2; the CO2 is then exhaled. Correct! Since the protons that were carried by hemoglobin are quickly sequestered by bicarbonate creating CO2, the pH changes very little. b. lower, there is more CO2 present. c. higher, there is more oxygen in the lungs d. lower, the protons (H+) that were combined with hemoglobin quickly bind to bicarbonate (HCO3-) to form CO2; the CO2 is then exhaled.
answer
higher, the protons (H+) that were combined with hemoglobin quickly bind to bicarbonate (HCO3-) to form CO2; the CO2 is then exhaled. Correct! Since the protons that were carried by hemoglobin are quickly sequestered by bicarbonate creating CO2, the pH changes very little.
question
`Carbon monoxide is poisonous because Select one: a. None of the options are correct. b. it binds hemoglobin 200 times better than oxygen. c. it binds hemoglobin 20 times less than oxygen. d. it binds hemoglobin 200 times less than oxygen.
answer
it binds hemoglobin 200 times better than oxygen. Correct! Carbon monoxide has an affinity for hemoglobin that is 200 times stronger than that of oxygen.
question
2,3 BPG stabilizes the _____ state(s) of hemoglobin. Select one: a. T Correct! 2,3 BPG stabilizes the T state of hemoglobin. This reduces hemoglobin's affinity for O2 and promotes O2 release to the tissues, in much the same way as low pH. b. R c. R and T d. None of the options are correct
answer
T Correct! 2,3 BPG stabilizes the T state of hemoglobin. This reduces hemoglobin's affinity for O2 and promotes O2 release to the tissues, in much the same way as low pH.
question
Even though the amino acid sequence between subunits of hemoglobin and myoglobin are not exactly the same, there are other similarities between the two proteins. Which level of protein structure is not found in both molecules? Select one: a. Secondary b. Tertiary c. Primary d. Quaternary
answer
Quaternary Correct! Myoglobin consists of a single subunit, while hemoglobin has four. Myoglobin has primary, secondary, and tertiary levels of protein structure, however, it does not have a quaternary structure. Any protein composed of only one subunit does not have quaternary structure.
question
In the deoxygenated state the heme is ____________, where as in the oxygenated state, the heme is _____________________. Select one: a. bent (non-planar), bent (non-planar) b. planar, bent (non-planar) c. bent (non-planar), planar d. planar, planar
answer
bent (non-planar), planar Correct! In the deoxygenated state the heme is bent (non-planar), where as in the oxygenated state, the heme is planar.
question
Fetal hemoglobin _____. Select one: a. has the exact same polypeptide chains as adult hemoglobin. b. is never in the R state. c. exhibits an oxygen binding curve that is the same shape as myoglobin oxygen binding curve. d. binds to oxygen tightly at lower oxygen concentrations since its R state is the preferred structure.
answer
binds to oxygen tightly at lower oxygen concentrations since its R state is the preferred structure. Correct! Fetal hemoglobin binds oxygen tightly at lower oxygen concentrations since its R state is the preferred structure.
question
When the blood pH is low, the heme is in_______________ shape. When the blood pH is high, the heme is in ______________shape. Select one: a. bent (non-planar), planar b. planar, bent (non-planar) c. bent (non-planar), bent (non-planar) d. planar, planar
answer
bent (non-planar), planar Correct! When the blood pH is low, the heme is in bent (non-planar) shape. When the blood pH is high, the heme is in the planar shape.
question
In which of the following patients is the planar conformation of the heme group in hemoglobin favored? Select one: a. In a firefighter who is brought to the emergency room after entering a burning building b. In a girl with diabetic ketoacidosis c. In an older woman with pneumonia and sepsis who has a blood pH of 7.1 d. In the muscle capillaries of a patient who is on a treadmill for a cardiac stress test
answer
In a firefighter who is brought to the emergency room after entering a burning building exercise is wrong because Exercise causes a decrease in pH in the surrounding tissues, which favors the bent heme conformation of the T state.