Practice Question

Questions

1. Why does SRP block the elongation factor binding site?

   1. To pause protein synthesis
   2. To expose the SRP’s receptor binding site
   3. It’s just bored
   4. 2 of the above [A-C]
   5. All of the above [A-C]

2. Which of the following statements(s) is/are true?

   1. Signal sequences that are found in the middle of ER transmembrane proteins are removed by signal peptidase
   2. Signal sequences that are found in the middle of an outer mitochondrial membrane protein are removed by signal peptidase
   3. Signal sequences that are found on the N-terminus of soluble ER resident proteins can be removed by signal peptidase
   4. Signal sequences always remain on the mature proteins and can never be removed
   5. 2 of the above

3. Gel-filtration chromatography can be used to separate proteins by:

   1. Charge
   2. Hydrophobicity
   3. Size
   4. Affinity for molecules
   5. None of the above

4. Your friend wants to isolate a cell from the tissue that it is a part of. She asks you what she can do. What do you say?

   1. You tell her that she can treat the tissue with enzymes that destroy proteins that anchor the cell to the matrix.
   2. You tell her that she can treat the tissue with agents that will bind to the calcium ions on which proteins at the cell-cell junction depend on.
   3. You tell her that she can add sodium dodecyl sulfate (SDS) to the tissue.
   4. You tell her 2 of the statements above, as they are both correct.
   5. You tell her she’ll need a good chainsaw and offer to lend her yours.

Answer key

1. a. To pause protein synthesis
2. c. Signal sequences that are found on the N-terminus of soluble ER resident proteins can be removed by signal peptidase.
3. c. Size
4. d. Both a and b are correct.