Question

• Opposite charges attract; like charges repel.
• Like dissolves like.
• “Stable” means “low energy” and unreactive, while “unstable” means “high energy” and reactive; and all things spontaneously become more stable over time (unless there is an input of energy), and in becoming more stable they release energy.

Explain how one or more of those principles apply to each of the following:

1. Vesicle membranes can “fuse” with target organelles’ membranes. (2.5 points)
2. ATP Synthase produces ATP. (2.5 points)

Answer 1

The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell.

In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion (exocytosis), uptake (endocytosis), and transport of materials within the plasma membrane. Alternatively, they may be prepared artificially, in which case they are called liposomes (not to be confused with lysosomes). If there is only one phospholipid bilayer, they are called unilamellar liposome vesicles; otherwise, they are called multilamellar. The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle.

Vesicles perform a variety of functions. Because it is separated from the cytosol, the inside of the vesicle can be made to be different from the cytosolic environment. For this reason, vesicles are a basic tool used by the cell for organizing cellular substances. Vesicles are involved in metabolism, transport, buoyancy control,, and temporary storage of food and enzymes. They can also act as chemical reaction chambers.