Hao Nguyen

1. What is a GTPase? Name the different GTPases discussed in class? What might happen to cellular functions in their absence? Propose how a cell might be able to cope in their absence.

2. The vesicular transport of cargo molecules like proteins requires the function of three types of coat proteins: clathrin, COP I, and COP II. Why are all three required? Can one or two out of the three types be sufficient for this function? Why are there so many other types of proteins that are involved in regulating vesicular transport? What happens to the pathway if one of these proteins is missing or present in a mutated, non-functional form?

3. Discuss the relationship among the following processes: flip-flop, membrane recycling via both vesicular transport and phospholipid exchange protein, and the function of flippase. (Does not apply to Fall 2009 lectures)

4. Describe the process of transmembrane transport into the endoplasmic reticulum. Why is this process necessary? Explain why this type of transmembrane transport can only move polypeptide across the membrane, but not folded proteins.

5. Also from lecture so far, we learned that many proteins and enzymes belong to specific families. Why should there be more than one protein for each cellular activity? Seems like a waste, don’t you think? Isn’t one protein/enzyme per activity enough?

6. Think about the importance of endosomes and vesicles, what is/are the function(s) of these transient organelles? What would happen to the endocytic and/or exocytic pathways if these organelles were absent?

7. Think about the types of molecules and/or atoms that are transported by diffusion versus passive transport (or facilitated diffusion) versus active transport. What are the differences and similarities between a carrier protein and a channel protein?

8. Can organelles still be transported from one area of the cell to another area in the absence of the cytoskeletons, especially if microtubules are missing? If so, how? If not, why not?

9. What is the function of the polarity in microtubules (that is, why do they have a plus end and a minus end)?

10. How are microtubules involved in exocytosis and endocytosis?

11. How is the polymerization and depolymerization of the various microtubule regulated? How are microtubules stabilized? What kind of exogenous substances can affect the stability of microtubules? How can these substances be used to study cell functions, like cell division and movement, using cell culture?

12. Consider the different types of intracellular transport: gated-transport versus transmembrane transport versus vesicular transport. What are the differences and similarities among these types of transport? What is it necessary to have so many types? What might happen to the cell if one type of transport were absent?

13. How are microtubules and microfilaments involved with cell division? What may happen to the cell when either the polymerization or depolymerization of these cytoskeletons is inhibited?