Chapter 7 Sapling

Which of the following statements about hemoglobin and myoglobin structure are true? Select the five true statements. home / study / science / biology / questions and answers / which of the following statements about hemoglobin ... Question: Which of the following statements about hemoglob... Save Which of the following statements about hemoglobin and myoglobin structure are true? Select the five true statements. 1. By itself, heme is not a good oxygen carrier. It must be part of a larger protein to prevent oxidation of the iron. 2. Molecular oxygen binds irreversibly to the Fe(II) atom in heme. 3. Heme is composed of an organic protoporphyrin component and a metal atom. 4. Each hemoglobin molecule can bind four oxygen molecules; each myoglobin can bind only one oxygen molecule. 5. Hemoglobin and myoglobin are heterotetramers. 6. Both hemoglobin and myoglobin contain a prosthetic group called heme, which contains a central iron atom. 7. Each iron atom can form six coordination bonds: One of these bonds is formed between iron and oxygen.

1. By itself, heme is not a good oxygen carrier. It must be part of a larger protein to prevent oxidation of the iron. 3. Heme is composed of an organic protoporphyrin component and a metal atom. 4. Each hemoglobin molecule can bind four oxygen molecules; each myoglobin can bind only one oxygen molecule. 6. Both hemoglobin and myoglobin contain a prosthetic group called heme, which contains a central iron atom. 7. Each iron atom can form six coordination bonds: One of these bonds is formed between iron and oxygen.

(a) Which of the following amino acids would you expect to produce a similar sickling effect if substituted for Val at position 6? Select all that apply.

Alanine Leucine

Which of the following are bound to hemoglobin when hemoglobin is in the R-state? Choose all that apply. CO2 Fe+2 O2 2,3-biphosphoglycerate Fe3+

Fe +2 O2

Hb, Mb, or Neither

Hb: O2 dissociation curve is an S shape O2 binds to the molecule & changes shape enahcing o2 binding cooperative binding pattern delivers O2 more efficiently Mb: O2 dissociation curve is hyperbolic Greater affinity to o2 Neither: CO2 binds at at an allosteric site, lowering O2 binding O2 binds irreversibly

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 loading of oxygen onto hemoglobin molecules in the lungs?

High partial pressure of O2 in the lungs

Shift left Shift right

Left: Hb (adult) replaced by infants Hb hb isolated from RBC and stripped of 2,3-biphosphoglycerate tetrameric hb is dissociated into its subunits Right: Ph drops from 7.4 to 7.2 CO2 conc in blood increases Conc of 2,3 biphosphoglycerate increases during acclimation to high atitutde

(b) Sickling occurs in deoxyhemoglobin S, but not in oxyhemoglobin S. Oxyhemoglobin has a small hydrophobic \"pocket\" in a β chain region located in the interior of the protein. In deoxyhemoglobin, however, this pocket is located on the surface of the protein. In deoxyhemoglobin S, Val 6 interacts with this surface pocket leading to aggregation of HbS. Choose two amino acids that would be reasonable candidates for the pocket-Val 6 interaction.

Leucine Phenylanaline

(c) How does HbS aggregation occur in sickle-cell anemia? Place the steps in the correct order. Note that deoxyhemoglobin is in the T state; oxyhemoglobin is in the R state.

No aggregation to sickled red blood cell: 1. O2 decreases due to vigorous exercise or high altitude 2. R state Hb shifts to T state Hb 3. Val interacts w/ the "pocket" of B chain on the other HbS 4. Additional T state HbS interact w/ growing aggregate to form an insouble fiber

The prosthetic group of Hb and Mb is ____ The organic ring component of heme is ___ Under normal conditions, the central atom of heme is ____ In _____the central iron atom is displaced .4 A out of the plane of the porphyrin ring system The central atom has ____ bonds: ____ to nitrogen atoms in porphyrin one to _____ residue and one to oxygen

heme porphyrin Fe +2 deoxyhemoglobin 6, 4, histidine

In the lungs, oxygen diffuses into the blood and is loaded onto hemoglobin for transport. In the tissues, oxygen is unloaded from hemoglobin and diffuses from the blood into nearby cells. What drives the diffusion of oxygen? partial P of co2 conc. of NO2 body T blood ph partial pressure of o2

partial pressure of O2

Which physiological changes naturally occur in teh body reduce hb's affinity for O2?

Accumulation of CO2 Decrease in pH