AUA REEL Questions (Helpful questions to prepare for the CAS Exam!) With Complete Solutions

A G-protein coupled receptor (GPCR) is a seven-pass transmembrane domain receptor that aids in the signaling cascade essential for various pathways in the body. Although the receptor is situated such that it is predominantly contained within the cell membrane, small portions can be found exposed to the aqueous environments on either side. One such portion is the region that allows for ligand binding on the extracellular surface. Which of the following amino acids could be found within the extracellular portion of the GPCR binding to ligands? (A) Arginine (B) Glycine (C) Isoleucine (D) Methionine correct answer: Arginine (Nonpolar) A student has isolated some nucleic acids from a new strain of bacteria. Examination of the RNA molecule reveals that the formation of a hairpin loop is essential for function. Which of the following is the most likely sequence of this region? (A) AGAUGAGAAUGCCU (B) AGCGTAGAGAAUCU (C) GCAGUGAGGAUCGC (D) GCGAUGAGAUGCGA (E) GCGAUGAGGAUCGC correct answer: GCGAUGAGGAUCGC GCGAUGAGGAUCGC can form a hairpin loop because the sequences (GCGAU and AUCGC) that flank the GAGG sequences are complementary and can form hydrogen bonds. Molecules interact via a variety of interactions in order to bind with one another. Covalent bonds are commonly stronger since they share electrons amongst the molecules. Which of the following sets of amino acids can participate in nonpolar covalent bonding? (A) Glutamate/Arginine (B) Glutamate/Glycine (C) Histidine/Aspartate