USABO Open Exam 2024 Question and Answers | 100%Verified & Updated | Graded A.

USABO Open Exam 2024 Question and Answers | 100%Verified & Updated | Graded A. 1. A student in lab is characterizing an unknown chain of amino acids and finds large numbers of lysine residues. Which of the following would be the location of their discovery? A. Alpha-helix interior. B. Histone tail. C. Magnesium-associated domain. D. Steroid center. E. Transmembrane domain. 2. Based on Graphs A and B below, would Taxol or colchicine be more likely to have a positive effect on cell division? A. Colchicine. It increases the amount of tubulin, so the spindle cannot form. B. Taxol. It increases the amount of tubulin, so the spindle cannot form. C. Colchicine. It decreases the amount of tubulin, so the spindle can form. D. Taxol. It increases the amount of tubulin, so the spindle can form. Graph A. The effect of Taxol on tubulin formation. Graph B. The effect of colchicine on tubulin formation. 3. Polypeptides like membrane transport proteins have a 3-D structure. Hydrogen bonding between the amino and carboxyl groups of individual amino acids most likely affects: A. Polar interactions between R-groups. B. Polar interactions in the tertiary structure. Page 1 Tubulin concentraton [Colchicine] Tubulin concentraton USABO Open Exam 2024 Question and Answers | 100%Verified & Updated | Graded A. C. Primary structure via non-polar interactions. D. Primary structure via covalent bonding. E. Secondary structure via polar interactions. 4. The molecule shown below is the substance pumiliotoxin produced by poison dart frogs. At which arrow could a hydrogen bond form? Image pumiliotoxin: 5. Consider the pathway below showing the degradation of toluene−a colorless liquid with a low to moderate water solubility. Toluene affects the central nervous system, but animals exposed to moderate to high levels of toluene also show harmful effects in their liver, kidneys, lungs and impaired immune function. Considering the general principles of energy metabolism, which of the following statements is TRUE regarding the pathway shown above? A. #1 in the pathway is an ATP generating step. B. # 1 in the pathway is a redox reaction; toluene is reduced. Page 2 A B C D E D C. The product of the toluene degradation at #2 is further degraded using glycolysis. D. The product of the toluene degradation pathway #2 is further degraded using beta-oxidation. E. The microorganism capable of utilizing this pathway cannot be used for bioremediation due to anabolism of toxic chemicals using toluenes as monomers. 6. A literature search reveals that NOX2 is an important protein complex responsible for generating the reactive oxygen species (ROS) in natural killer (NK) cells. RNA interference (RNAi) was used against NOX2 in NK cells. ROS production was measured with a general fluorescent ROS probe and compared to the control NK cells. The general ROS probe fluorescence intensity was significantly lower in the experimental group when compared to the control NK cells. Your lab is attempting to uncover the intracellular mechanism of ROS production in NK cells. The graduate student conducting the experiment insists that NOX2 was functionally knocked out in the cell line using synthetic single-stranded RNA for RNAi and concludes that the functional removal of NOX2 by RNAi results in no ROS production. Your guidance to your graduate student is I. DNA interference should be used in lieu of RNAi. II. A specific inhibitory peptide to NOX2 translation (protein interference) should be used in lieu of RNAi. III. RNAi is not 100% efficient and there may be some NOX2 mRNAs that are not degraded. IV. Synthetic double-stranded RNA should have been used for RNAi, not single-stranded RNA A. I and II. B. I, II, and III. C. I, II, III, and IV. D. II, III, and IV. E. III and IV.