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Bohr shift

An effect by which an increase of carbon dioxide in the blood and a decrease in pH results in a reduction of the affinity of hemoglobin for oxygen. Right shift on curve

Which state(s) of hemoglobin would predominate if the blood concentration of 2,3‑BPG increased?

BPG can only bind in T state

Select all statements that correctly describe hemoglobin and myoglobin structure. Molecular oxygen binds irreversibly to the Fe(II) atom in heme. Both hemoglobin and myoglobin contain a prosthetic group called heme, which contains a central iron (Fe) atom. The heme prosthetic group is entirely buried within myoglobin. By itself, heme is not a good oxygen carrier. It must be part of a larger protein to prevent oxidation of the iron. Each hemoglobin or myoglobin molecule can bind four oxygen molecules. Hemoglobin is a heterotetramer, whereas myoglobin is a monomer. Each iron atom can form six coordination bonds. One of these bonds is formed between iron and oxygen.

Both hemoglobin and myoglobin contain a prosthetic group called heme, which contains a central iron (Fe) atom. By itself, heme is not a good oxygen carrier. It must be part of a larger protein to prevent oxidation of the iron. Hemoglobin is a heterotetramer, whereas myoglobin is a monomer. Each iron atom can form six coordination bonds. One of these bonds is formed between iron and oxygen.

Select the scenarios which, according to the Bohr effect, result in hemoglobin's release of bound oxygen. Carbon dioxide levels in the blood increase. The concentration of hydrogen ions in the blood increases. The pH of blood increases. Oxygen levels in the blood increase.

Carbon dioxide levels in the blood increase. The concentration of hydrogen ions in the blood increases.

How does HbF's affinity for O2 compare with HbA's affinity for O2 in the presence of 2,3‑BPG?

HbF should have a higher affinity for O2 relative to HbA

How should replacing the His residues found in HbA with the Ser residues found in HbF affect the binding of 2,3‑BPG to HbF?

HbF should have a lower affinity for 2,3 BPG relative to HbA

How does hemoglobin function as a pH buffer?

Hemoglobin binds hydrogen ions after CO2 ENTERS the rbc

O2 binding favors R state or T state?

R state

R state or T state: high CO concentration

R state

R state or T state: high O2 concentration

R state

What conformational states of hemoglobin should haave a higher affinity for CO?

R state

Since CO binds to hemoglobin like O2, what is the effect of one molecule of CO binding to hemoglobin?

The affinity of neighboring subunits for both O2 and CO increases

In this case, what happened as CO was transported by the mother's blood?

The fetus, who expressed HbF, had a higher affinity for CO than did the mother, who expressed HbA. Thus the fetus essentially pulled the CO out of the mother's blood, allowing her to survive.

Would a molecule of O2 bind to one of the hemes of a hemoglobin molecule in the T state, which has no molecules of O2 bound?

Yes, but the molecule of O2 would bind weakly because the T state has a low affinity for O2.

Hemoglobin Kansas

a hemoglobin variant in which a threonine residue is substituted for an asparagine at residue 102 of the beta-chain; destabilizing the R state (lower affinity, right shift)

based on how O2 binding affects the affinity of neighboring hemoglobin subunits, O2, is an ______________ ____________ allosteric modulator.

activating homotropic

What does HbF's higher affinity for O2 imply about its affinity for CO?

also high affinity for CO

Identify the factors that directly favor the unloading of oxygen from hemoglobin in the blood near metabolically active tissues. an increase in blood temperature near the tissues the presence of a pressure gradient for oxygen an exchange of ions in the erythrocytes an increase in blood acidity near the tissues

an increase in blood temperature near the tissues the presence of a pressure gradient for oxygen an increase in blood acidity near the tissues

Which methods of energy production contributes to a decrease in pH?

both anaerobic (lactic acid) and aerobic (carbon dioxide--> carbonic acid)

loss of quaternary structure

curve 1 (closest to zero)

no perturbation

curve 3

For an decrease in pH, will the oxygen-binding affinity of hemoglobin increase, decrease, or not change.

decrease

For an increase in body temperature, will the oxygen-binding affinity of hemoglobin increase, decrease, or not change.

decrease

favors T state

decrease pH increased CO2 decreased O2

heterotropic allosteric regulation

different ligand affects binding of the normal ligand

homotropic allosteric regulation

effector molecule is also enzymes substrate

As oxygen binds to this molecule the shape of the molecule changes, enhancing further oxygen binding

hemoglobin

binding pattern for this molecule is considered cooperative

hemoglobin

oxygen dissociation curve is sigmoidal in shape

hemoglobin

What would be the net effect of increasing the concentration of 2,3‑BPG in the blood?

hemoglobin's O2 affinity decreases

For a decrease in partial pressure of CO2, will the oxygen-binding affinity of hemoglobin increase, decrease, or not change.

increase

Hemoglobin is a protein in red blood cells that binds to oxygen. Which physiological changes that naturally occur in the body reduce hemoglobin's affinity for oxygen?

increase in temperature decrease in pH increase in CO2

a decrease in CO2

left shift (curve 2)

an increase in pH

left shift (curve 2)

Which factors are associated with sickling of red blood cells in sickle cell anemia disease?

low pH, dehydration, high temperature, overexertion, oxygen tension from high altitude increase 2,3 bpg, co2

All of the cells in the body need oxygen. Hemoglobin molecules in red blood cells transport oxygen through the bloodstream. Oxygen is loaded onto hemoglobin molecules in the lungs and unloaded from the hemoglobin molecules in the tissues. What drives the unloading of oxygen from hemoglobin molecules in the tissues?

low partial pressure of O2 in the tissues

Since HbF has a _______ affinity for 2,3 BPG than does HbA, more molecules of HbF are in the ____ state than are molecules of HbA. So,HbF will always have a ____________higher affinity for O2 relative to HbA

lower, R state, higher

oxygen dissociation curve is hyperbolic in shape

myoglobin

this molecule has a greater affinity for oxygen

myoglobin

carbon monoxide binds at an allosteric site, lowering oxygen binding affinity

neither hemoglobin or myoglobin

oxygen binds irreversibly to this molecule

neither myoglobin or hemoglobin

Which 2 molecules are bound to hemoglobin when it's in the R state?

oxygen and Fe2+

Considering the structure of 2,3‑BPG, what type of residues do you suspect line the cavity between the β subunits where 2,3‑BPG binds?

positive charge bc BPG is a deprotonated form (conjugate base)

His residue can become ___________ and ____________charged enabling them to strongly interact with the ___________charged group of 2,3 BPG.

protonated, positively, negatively

an increase in 2,3-bpg

right shift (curve 4)

The oxygen-hemoglobin dissociation curve describes the percent oxygen saturation of hemoglobin as a function of the partial pressure of oxygen (PO2) in the surrounding fluid. As the PO2 increases on the horizontal axis, the oxygen saturation percentage also increases on the vertical axis. In comparison to that of adult hemoglobin, how is the fetal oxygen-hemoglobin dissociation curve shifted?

to the left, indicating a higher O2 affinity of fetal hemoglobin

true or false nitrogen has no effect on hemoglobin

true

Which 3 are true about the blood buffering system?

utilizes the H2CO3/HCO3- conjugate acid/base pair maintains the pH of blood near 7.4 is facilitated by the enzyme carbonic anhydrase, which interconverts carbon dioxide and water to carbonic acid (ionizes into bicarbonate and H+)