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

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