Exam 6: Cell Membranes

The LDL receptor is an integral protein that crosses the plasma membrane, with portions of the protein extending both outside and into the interior of the cell. The amino acid side chains (R groups) in the region of the protein that crosses the membrane are most likely

When vesicles from the Golgi apparatus deliver their contents to the exterior of the cell, they add their membranes to the existing plasma membrane. This is made possible by

The process of random movement of molecules toward a state of equilibrium is called _______.

The process by which the plasma membrane engulfs large particles or even whole cells is called _______.

A marathon runner has just arrived in the emergency room with severe dehydration, and the physician must decide which type of solution to pump into his veins: pure water, 0.9 percent saline, or 1.5 percent saline. In order to be certain, blood samples are treated with each solution and observed under a microscope. Describe what is likely to happen to the blood cells when exposed to each solution. (Hint: Blood cells are approximately 0.9 percent saline.) Which solution should the physician choose for rehydrating the runner?

Osmosis moves water from a region of _______ to a region of _______.

Cell adhesion molecules of the same type are called _______.

Which of the following types of junctions are responsible for communication between cells?

If a cell placed within a solution shrinks, the solution is _______ relative to the cell.

In the parietal cells of the stomach, the uptake of chloride ions is coupled to the transport of bicarbonate ions out of the cell. This type of transport system is called

Membrane proteins covalently bonded to carbohydrates are called _______.

Receptor-mediated endocytosis

When a membrane is prepared by freeze-fracture and examined under the electron microscope, the exposed interior of the membrane bilayer appears to be covered with bumps. These bumps are

Biological membranes are composed of a continuous phospholipid bilayer in which proteins are embedded. This general design is known as the _______ model.

Which type of membrane protein would likely be most easily removed in a laboratory experiment?

The rate of diffusion can be affected by

In addition to the bilayer lipids and proteins, membranes may contain _______ in the form of _______ and _______.

Bacterial cells are often found in very hypotonic environments. Which of the following characteristics keeps them from taking in too much water from their environment?

Which statement about membrane proteins is not true?

Active transport differs from passive transport in that active transport