5. Cell Components

Which part of the nucleus is responsible for assembling ribosomes and ribosomal RNA?

Which structure is part of the endomembrane system? (A) mitochondrion (B) Golgi apparatus (C) chloroplast (D) centrosome

Which of the following results provided evidence of a discrete nuclear localization signal somewhere on the nucleoplasmin protein? a. The nucleoplasmin protein was small and easily slipped through the nuclear pore complex. b. After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus. c. Removing the tail from the nucleoplasmin protein allowed the core segment to enter the nucleus. d. The SRP bound only to the tail of the nucleoplasmin protein, not the core segment.

Molecular zip codes direct molecules to particular destinations in the cell. How are these signals read? a. They bind to receptor proteins. b. They enter transport vesicles. c. They bind to motor proteins. d. They are glycosylated by enzymes.

Cells that line your intestines are known to possess a large number of membrane proteins that transport small molecules and ions across the plasma membrane. Which of the following cell structures would you expect to be required for this characteristic of the cells? a. the endoplasmic reticulum b. peroxisomes c. lysosomes d. the cell wall

Most of the proteins that enter the nucleus possess a nuclear localization signal (NLS), even if they are small enough to pass through the nuclear pore complex unhindered. Why would a small protein have an NLS, when it naturally diffuses across the nuclear pore complex without one?