Chapter 7 - Cell Membranes

Identify all processes that are of passive diffusion.

• small, nonpolar molecules moving across membrane

• all carrier proteins

• osmosis

• all channel proteins

The Human/Mouse Cell Fusion experiment confirmed what? (Select all that applies)

• Phospholipids of a membrane exist in a fluid state

• Cholesterol is a good fluidity buffer

• Proteins in the membrane can flip over

• Phospholipids and proteins move laterally

You are observing an integral protein and come to the conclusion that only one part of the protein is sticking out of the membrane. Which amino acid would you expect to find in this "exposed" part of the protein?

• Glycine

• Proline

• Leucine

• Tyrosine

Which types of molecules cannot be transported directly across the phospholipid membrane?

• Nonpolar

• Polar

• Small

• Large

When considering the process of osmosis, what are you assuming?

• The membrane barrier is selective to water but not to solutes.

• The membrane barrier is selective to solutes but not to water.

• Osmosis will occur unchecked until both solutions are 100% isotonic to each other.

• The solutes will eventually repel the incoming water and stop osmosis.

Some protist organisms like paramecium can resist bursting by osmosis with the help of what kind of internal structure?

• Contractile ring

• Central Vacuole

• Contractile vacuole

• Cilia and Flagella

Cystic Fibrosis is a condition in which a faulty transport protein becomes malfunctioned and prevents the movement of Cl- ions. What explains the resulting mucus buildup in air passageways?

• [Cl-] is higher inside the cell, resulting in the cell excreting other ions to account for the - charge.

• [Cl-] is higher inside the cell, resulting in osmosis occurring and water entering the cell.

• [Cl-] is higher outside the cell, resulting in the surrounding cells producing mucus to control the ions.

• [Cl-] is higher outside the cell, resulting in osmosis occurring and water entering the air passageways.

Intestinal cells commonly have a type of membrane carrier protein that transports Na+ and glucose into the cell. What could this protein be called?

• A symport/symporter

• An active transport pump

• A facilitated channel protein

• An antiport/antiporter

The Na+/K+ pump results in an electrochemical gradient. What are the charge distributions in/out of the cell?

• positive internal environment

• negative internal environment

• no charge differences

Plants also have active transport pumps. What is the purpose of their proton pump?

• To use up the excess ATP within the plant cell

• To bind with and neutralize toxic substances

• To promote the diffusion of sucrose via channel protein into the cell

• To promote the transport of sucrose and H+ into the cell via a symporter