Lecture 10: Cell compartments

Question 1

• Know and compare the cellular components of prokaryotic and
eukaryotic cells. (You are responsible for knowing all of the
material covered in the Cell Structure Assignment)

Answer 1

refer to assignment.

Question 2

• Know and compare protein sorting in the cytosol and protein
sorting in the rough ER.

Answer 2

In cytosol:
• Proteins on free ribosomes: produced
in the cytosol and are sorted to their final
destination after translation
• These proteins are directed to their
proper cellular compartments via
signal sequences

In rough ER:
• Regions of ER membrane that contain ribosomes: sites of protein
synthesis

Question 3

• Describe the process of transmembrane protein targeting.

Answer 3

• Proteins with signal anchor sequences are threaded through channel in the ER membrane until the signal-anchor sequence is encountered.
• The ER channel releases the protein into the membrane.
• When translation is complete, the protein remains in membrane.