Very small gold beads are injected into a cell, then an hour is allowed to pass.
ID: 165590 • Letter: V
Question
Very small gold beads are injected into a cell, then an hour is allowed to pass. Under examination, the gold beads are found in both the cytoplasm and the nucleus. In a second experiment where larger gold beads are injected, they are only found in the cytoplasm. In a third experiment, NLS tags are added to the large gold beads, and after an hour beads are seen in both the cytoplasm and nucleus. From this experiment one could conclude that
Very small gold beads are injected into a cell, then an hour is allowed to pass. Under examination, the gold beads are found in both the cytoplasm and the nucleus. In a second experiment where larger gold beads are injected, they are only found in the cytoplasm. In a third experiment, NLS tags are added to the large gold beads, and after an hour beads are seen in both the cytoplasm and nucleus. From this experiment one could conclude that
1.nuclear import mainly relies on diffusion to get molecules into the nucleus
1.nuclear import mainly relies on diffusion to get molecules into the nucleus
2.the nuclear localization mechanism is nonspecific as long as the tag is present 3.the nuclear localization sequence is lysine rich 4.the gold beads have an inherent import signalExplanation / Answer
Answer: (2) The nuclear localization mechanism is nonspecific as long as the tag is present.
The transport of nuclear proteins through nuclear pore complexes can be directly visualized by coating gold particles with a nuclear localization signal, injecting the particles into the cytosol, and then following their fate by electron microscopy.
Studies with various sizes of gold beads indicate that the opening of nuclear pore (NPC) can dilate up to about 26 nm in diameter during the transport process. A structure in the center of the nuclear pore complex seems to function like a close-fitting diaphragm that opens just the right amount to let transport substrates pass.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.