Question

Which of the following is NOT true regarding sickle-cell disease? Select one: a. It is due to a mutation resulting in a hydrophilic amino acid. b. It is a cause of anemia. c. It is due to a hereditary hemoglobin defect. d. It is caused by a recessive allele that modifies the structure of hemoglobin. O e. It is advantageous in that it can protect carriers against malaria.

Answer 1

1. The statement which is NOT true for sickle cell anemia is it is due to mutation resulting in a hydrophilic amino acid. In sickle cell anemia, the mutation occurs in beta chain of hemoglobin where glutamic acid is replaced by valine. The resulting amino acid valine is hydrophobic in nature and not hydrophilic.

2. The statement which does not lead to polycythemia is high blood sodium levels. Polycythemia is excess production of red blood cells and is caused by hypoxia, emphysema, high altitude, bone marrow cancer, huge excercise, etc.

3. The statement which is correct about ascending loop of Henle's is the ascending loop of Henle's is pumping out ions but is impermeable to water. This leads to absorption of ions which leaves diluted urine.

4. The statement which is correct about glomerular filtration rate is constriction of afferent arteriole. Glomerular filtration rate is decreased by constriction of afferent arteriole and dilation of efferent arteriole and is increased by increased blood pressure.