5. Cell Components

A researcher made an interesting observation about a protein made by the rough endoplasmic reticulum and eventually found in a cell's plasma membrane. The protein in the plasma membrane was actually slightly different from the protein made in the ER. The protein was probably altered in the __________.

Consider a protein that is made in the rough endoplasmic reticulum. You observe that when the synthesis of the protein is completed, the protein is located in the ER membrane. Where else in the cell might this protein be found?

A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.

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

Which structure is not part of the endomembrane system? a. nuclear envelope b. chloroplast c. Golgi apparatus d. plasma membrane

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?

In which cell would you find the most smooth ER? a. pancreatic cell that secretes digestive enzymes b. ovarian cell that produces estrogen (a steroid hormone) c. muscle cell in the thigh of a long-distance runner d. white blood cell that engulfs bacteria

In which cell would you find the most rough ER? a. pancreatic cell that secretes digestive enzymes b. ovarian cell that produces estrogen (a steroid hormone) c. muscle cell in the thigh of a long-distance runner d. white blood cell that engulfs bacteria

Describe the pathway of the protein hormone insulin from its gene to its export from a cell of your pancreas.