What are three attributes of mitochondria and chloroplasts that suggest they were once free-living bacteria?

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.

How does the hydrolysis of ATP result in the movement of a motor protein along a cytoskeletal filament?

Which of the following cell structures would you expect to be most important in the growth of bacteria on the surface of your teeth?

a. Cell wall

b. Fimbriae

c. Flagella

d. Cilia

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?

The eukaryotic cytoskeleton is a highly dynamic network of filaments and motor proteins. Which of the following correctly describe activities of these cytoskeletal components? Select True or False for each statement.

T/F Myosin motors walk toward the plus ends of intermediate filaments.

T/F Dynein motors are responsible for the whip-like movement of eukaryotic flagella.

T/F Kinesin motors move vesicles along tracks toward the microtubule-organizing center.

T/F Actin filaments are required for cytoplasmic streaming.

When analyzing a sample of cells from a patient, you find the lysosomes are filled with undigested material. This observation makes you think that the lysosomes are not functioning properly. What are three different defects that could be responsible for malfunctioning lysosomes?

George Palade's research group used the pulse–chase assay to elucidate the secretory pathway in pancreatic cells. If they had instead performed this assay on muscle cells, where would you expect the labeled proteins to end up during the chase?

(Muscle cells consist primarily of actin and myosin filaments and have high energy demands for muscle contraction.)