Proteins travel from the ER to the Golgi in COP-II coated vesicles. How is cargo incorporated into these vesicles? O A. Cargo is transported through a translocon to the vesicle B. Cargo is bound by a receptor that directly associates with COP II through an adaptor protein OC All cargo has the KDEL signal sequence that is recognized by the KDEL receptor OD. Cargo is bound by the mannose 6 phosphate receptor that associates with COP II through an adaptor protein

The LDL receptor is internalized via endocytosis every ten minutes and recycled to the membrane. How does the cell recycle the receptor and not the ligand (in this case LDL)? A. The high pH (~10) of the early endosome causes dissociation of LDL from the receptor and the receptor is segregated into recycling endosomes. B. The low pH (~5) of the early endosome causes dissociation of LDL from the receptor and the receptor is segregated into recycling endosomes. O C. A targeting sequence on the ligand sorts it to the late endosome/lysosome. D. This is an error-prone process, the ligand often gets recycled accidentally.

AAA is a protein found in both the cytosol as well as the nucleus. In its active state, it helps to facilitate the movement of proteins into and out of the nucleus. Specifically, AAA-alpha and AAA-beta binds to receptors on the nucleus and allows for materials to enter or exit through the channels associated with the receptors. They also play a role in dropping off cargo that import and export receptors hold onto. AAA functions are controlled by two other proteins: BBB and CCC. BBB binds onto AAA, while CCC removes BBB from AAA when they are bound. As a result, there is a BBB and CCC concentration gradient that forms between the cytosol and nucleus. During prophase I, is there a concentration gradient for BBB and CCC between the cytosol and the nucleus? Why? Is this also the case during the other phases of meiosis or the cell cycle?

The G-protein Ras is involved in proliferative signaling, and is mutated is a large fraction of human cancers. Almost all mutations in Ras mutate the glycine at codon 12. These mutations lock Ras in an active conformation. How will the GTPase activity of a Ras protein with a G12 mutation compare to a normal Ras protein without the mutation? (10 words maximum)