Tutor profile: Pedro C.

1. The pronoun ellos may refer to _____. A) A Female B) A Male C) A group of females and males D) A female group

C) A group of females and males

Which among the following is not a property of Ionic bond? a) Losing of electrons b) Gain of electrons c) Sharing of electrons d) Transfer of electrons

C) Sharing Electrons

Once a vesicle has formed, the vesicle only will fuse with a specific type of target membrane. In some cases, different vesicles formed at the same donor membrane have different target membranes. Based only on the basic vesicle transport mechanisms discussed in this course, explain how the target membrane specificity is achieved. Describe the structure and function of any important proteins.

Target membrane specificity is achieved by 2 predominant methods a long-range association known as tethering and a short-range know as docking. The tethering process is driven by Rabs which are GTPases that have an active GTP state and inactive GDP state. These proteins also have a covalently attached lipid which is protected by GDI to keep itself soluble in the cytosol but in the GTP state, it is exposed and interacts with the membrane. similarly to the above Rabs active state is promoted by GEFSs Once in the active state Rabs are able to bind to one or more RAB effector proteins that only bind in the active state. Some of these Rab effectors are membrane-bound and help drive tethering to bring membranes close together. The other component of this is driven once membranes are in close proximity which is when docking can begin docking is driven by transmembrane SNARE proteins which help to drive the membrane fusion. V-snares are comprised of a single protein with 1 helical domain while t-SNAREs are comprised of 3 proteins each with their own helical domain. These SNARES interact with each other to form a 4 helix bundle that is then able to function like a zipper with high specificity and drive the fusion of membranes.