Test Bank Molecular Biology of the Cell 6th Edition Alberts

Test Bank Molecular Biology of the Cell 6th Edition Alberts 35. The marking of a protein by polyubiquitylation to signify degradation & A. requires the hydrolysis of one ATP molecule to ADP per polyubiquitin chain. B. involves covalent attachment of the target protein to the E1 enzyme. C. is carried out by the proteasome complex. D. is typically done on an arginine residue in the target protein. E. involves the recognition of the target protein by an E23E3 ligase. 36. The SCF ubiquitin ligase can recognize and mark various target proteins at different stages of the cell cycle. In this complex, & A. different F-box subunits recognize different target proteins. B. the F-box subunit and the E2 ubiquitin-conjugating enzyme are at the opposite ends of the C-shaped molecule. C. a scaffold protein arranges the other subunits such that the two ends of the complex are separated by a gap. D. the use of interchangeable parts such as the F-box subunits makes economical use of the genetic information and allows for rapid evolution of new functions. E. All of the above. 37. In terms of molecular function, what do Ras and myosin have in common? A. They normally bind to GTP. B. They couple the hydrolysis of a bound nucleoside triphosphate to protein movements. C. They switch between two distinct conformations controlled by protein phosphorylation and dephosphorylation. D. They are multisubunit proteins and contain a scaffold subunit. E. All of the above. 38. The compound GDPNP is a GTP analog that can bind to GTPases in the same way as GTP. However, unlike GTP, it cannot undergo the hydrolysis reaction that normally releases Pi. Therefore, & A. GDPNP and GDP bind to the same conformation of a GTPase. B. a GDPNP-bound Ras is constitutively active. C. a GDPNP-bound EF-Tu cannot bind to tRNA molecules. D. binding of GDPNP to EF-Tu allows multiple cycles of tRNA binding and release without the use of free energy.