In sickle-cell disease, a glutamate -> valine substitution results in the formation of Hb5 (sickle cell hemoglobin) molecules
that: a. Stabilize the wall of the red blood cell against oxidative damage b. aggregate abnormally to form fibers and cannot adequately carry oxygen c. have abnormally High Affinity to bind oxygen d. cause high levels of repulsion between neighboring Hb5 molecules
b. aggregate abnormally to form fibers and cannot adequately carry oxygen
Explanation:
The sickle cell hemoglobin is an abnormal form of hemoglobin. As the sickle cell hemoglobin release oxygen to the interstitial fluid, it forms long, stiff, and rod-like fibers. These aggregates of hemoglobin tend to bend the erythrocyte into a sickle shape. The sickled erythrocytes rupture easily and do not move easily through blood vessels. Sickled cells tend to stick together and form clumps which in turn cause blockages in blood vessels. Therefore, the presence of sickle cell hemoglobin adversely affects the ability of RBCs to carry oxygen.
Because double bonds cause the hydrocarbon chain to bend. Therefore, the fatty acids cannot compact tightly together, reducing the van der Waals interaction between the fatty acids. The melting point of fatty acids is also affected by chain length. The longer the hydrocarbon chain is, the higher the melting point.
