Couple of Questions

[Shenamic]

Dear Somalidoc User, Here are Couple of Questions to share with you. The Two question were in my Biochemistry Quiz which I attended Today ( 18/05/11).

1. A child presents with severe growth failure, accelerated aging that causes adult complications such as diabetes and coronary artery disease, and microcephaly (small head) due to increased nerve cell death. In vitro assay of labeled thymidine incorporation reveals decreased levels of DNA synthesis compared to controls, but normal-sized labeled DNA fragments. The addition of protein extract from normal cells, gently heated to inactivate DNA polymerase, restores DNA synthesis in the child?s cell extracts to normal. Which of the enzymes used in DNA replication is likely to be defective in this child?

a. DNA-directed DNA polymerase
b. Unwinding proteins
c. DNA polymerase I
d. DNA-directed RNA polymerase
e. DNA ligase

2. A newborn with tachypnea and cyanosis (bluish color) is found to have a blood pH of 7.1. A serum bicarbonate is measured as 12 mM, but the blood gas machine that would determine the partial pressures of oxygen (PO2) and carbon dioxide (PCO2) is broken. Recall the pKa of 6.1 for carbonic acid (reflecting the HCO3−/CO2 equilibrium in blood) and the fact that the blood CO2 concentration is equal to the PCO2 in mmHg (normal value = 40 mmHg) multiplied by 0.03. Which of the following treatment strategies is indicated?

a. Administer oxygen to improve tissue perfusion and decrease metabolic acidosis
b. Administer oxygen to decrease respiratory acidosis
c. Increase the respiratory rate to treat respiratory acidosis
d. Decrease the respiratory rate to treat respiratory acidosis
e. Administer medicines to decrease renal hydrogen ion excreta

Good Luck!