Question

1.  Regulation of protein activity by phosphorylation requires ________ activity.

1. kinase
2. ubiquitin
3. protease
4. phosphatase
5. 20S proteasome

2. Which of the following are substrates used by RNA polymerase in the process of transcription?

1. DNA template
2. ribonucleotie triphosphates
3. deoxyribonucleotide triphosphates
4. inorganic phosphates
5. proteins

3.  The ribosome

1. is an enzyme complex made entirely of protein molecules.
2. directs elongation of polypeptides.
3. is organized into 2 subunits whose sizes are designated in Svedberg (S) units.
4. is not used by cells that secrete large amounts of protein.
5. is both b and c.

4. Characteristics of a buffer are:

1. They help maintain the cell’s pH.
2. Their buffering capacity is independent of all other factors.  
3. They must be a strong acid or strong base.
4. Both a and b.
5. Both a and c.

5. Logical use(s) of a cystolic protein would be:

1. To associate with extracellular molecules.
2. Transport through biomembrane.
3. Anchoring and signaling.
4. To activate or inactivate a cell surface receptor.
5. To prevent unwanted molecules from passing across the biomembrane and into the cell.

6. Which of the following factors increase the rate of simple (passive) diffusion of a solute __________ across a phospholipid bilayer?

1. increased ability of the solute to dissolve in the membrane
2. increased hydrophilicity of the solute
3. increased membrane thickness
4. all of the above
5. none of the above

7. The major classes of CAMs include:

1. cadherins
2. fibronectin
3. Ig-superfamily CAMs
4. P-selectins
5. steroids

8. Movement of phospholipids from one leaflet to the other

      a. occurs routinely.

      b. requires cholesterol.

      c. requires flippases.

      d. is impossible.

9. Which of the following plays a role in the degradation of proteins?

      a. chaperonin

      b. ubiquitin

      c. proteasome

      d. b and c

      e. all of the above

10. Reversible chemical interactions are mediated by

1. electrostatic interactions.
2. hydrogen bonds.
3. van der Waals interactions.
4. all of the above.
5. none of the above.

Answer 1

1. Kinase An enzyme that catalyzes the transfer of phosphate groups to different substrates from high-energy, phosphate-donating molecules.

2. Ribonucleotie triphosphates is the substrate used by RNA polymerase.

3. The ribsome is directs elongation of polypeptides.and organized into 2 subunits whose sizes are designated in Svedberg (S) units both b and c.

4. They help maintain the cell’s pH and their buffering capacity is independent of all other factors. both a and b

5. Anchoring and signaling. Cytosolic protiens are invovled in anchorage and in signal transductions.

6. increased ability of the solute to dissolve in the membrane, makes the solute diffusible.

7. Cadherins, Ig-superfamily CAMs. P-selectin is a subclass of selectin which is a class of CAM.

8.Phospholipid movement requires flippase enzyme.

9.Ubiquitin and proteasome are involved in protien degradation.

10.All of the above, electrostatic interactions, hydrogen bonds,.van der Waals interactions.