RQ4.Answer = F. Tissue plasminogen activator (TPA) converts plasminogen to plasmin that degrades fibrin (fibrinolysis), thereby degrading the clot (thrombolysis). Aspirin, an inhibitor of cyclooxygenase, is an antiplatelet drug. Antithrombin III (ATIII) removes thrombin from the blood, and its action is potentiated by heparin. Activated protein C (APC) complex cleaves the accessory proteins factor (F)Va and FVIIIa. ATIII and APC are involved in anticoagulation. FXIII is a transglutaminase that cross-links the fibrin meshwork. Vitamin K is a fat-soluble vitamin required for the γ-carboxylation of FII, FVII, FIX, and FX. Warfarin prevents regeneration of the functional, reduced form of vitamin K. RQ5.Answer = D. In hypoxia, substrate-level phosphorylation in glycolysis provides ATP. Oxidative phosphorylation is inhibited by the lack of O2. Because the rate of ATP synthesis by oxidative phosphorylation controls the rate of cellular respiration, electron transport is inhibited. The resulting rise in the ratio of the reduced form of nicotinamide adenine dinucleotide (NADH) to the oxidized form (NAD+) inhibits the tricarboxylic acid cycle and the pyruvate dehydrogenase complex. RQ6.Answer = D. Fluorescently labeled nucleotides allow the base sequence of the DNA of interest to be determined. Complementary DNA (cDNA) is generated from processed messenger RNA and would not contain the promoter. Dideoxynucleotides lack the 3′-OH needed to form the 3′→5′-phosphodiester bond that joins the nucleotides and, thus, will terminate DNA synthesis. Genomic DNA obtained from white cells isolated from a blood sample would be the source of the DNA.
Case 1: Answers to Thought Questions