Exam

Cell Bio

Cumulative Questions for Final Exam

The following questions deal with cellular functions in amoeba - freshwater, unicellular organisms. The genes/proteins (Bfd/NBFD) in this question are fictional – you can’t Google them.

1. (10) Bfd is a gene that encodes for a protease that functions in the lysosome of phagocytic amoeba to degrade foreign proteins. Describe the protein processing (translation and post-translational modifications) and transport processes involved in creating a functional BFD protein. [Things to consider: How does BFD get where it needs to be? What needs to happen for it to be functional?]

2. (4) NBFD is a gated ion channel that is found in the plasma membrane of many amoeba. NBFD binds food and triggers phagocytosis by mediating the opening of Ca2+ channels in the cell’s plasma membrane. When these channels open, would Ca2+ enter or leave the cell? Explain your answer.

3. (5) Describe the process of phagocytosis from the time the amoeba senses food until the macromolecules are released into the cytoplasm.

4. (6) Amoeba use aerobic respiration to acquire energy from the food they ingest whereas some of the bacteria that amoeba eat use fermentation. Which of these cells (amoeba or bacteria) would be more affected if there were an accidental spill of cyanide into the lake where these cells lived? Compare and contrast their metabolic processes to support your answer.

5. (4) What other similarities and differences exist in the basic cellular structures and functions between the amoeba and its bacterial prey?

6. (10) Pyruvate kinase (PK), a key regulatory enzyme in glycolysis that is utilized by both amoeba and bacteria, is inhibited by ATP and Acetyl-CoA and activated by fructose-1,6-bisphosphate. Below is a Lineweaver-Burk plot of PK activity without ATP and with increasing concentrations of ATP. Is ATP a competitive or non-competitive inhibitor of PK? Explain your answer. Estimate the...