Exam 4: Cell Membranes, Transport, and Communication

Cell surface receptors of chemical messages are made of

Gap junctions allow large molecules to move from cell to cell.

Muscle cells require high concentrations of calcium to function properly.As a result,these cells use ________ transport to move calcium from areas of low concentration outside the cell into the cytoplasm.

Which of the following statements about hormones is FALSE?

Cells in the liver typically acquire cholesterol by receptor-mediated ________.

A white blood cell at the site of a puncture wound engulfs a large cluster of bacteria forming a large internal vesicle.This is an example of

Active transport requires

All movement,including that of diffusing molecules,requires a small expenditure of energy;which of the following small sources of energy is most likely to make diffusion possible across the cell membrane from the cell exterior into the cell interior?

The arrows in the following figure show the movement of water across the cell wall and plasma membrane of a plant cell. For water to move in the direction indicated,the solution surrounding the cell must be

After eating a meal high in carbohydrates,the pancreas begins releasing the hormone insulin by the process of ________.

Protein-lined tunnels that span the small intercellular space separating adjacent cells and that allow the rapid and direct passage of ions and small molecules,including signaling molecules,are called ________.

When placed in a 2 percent sucrose solution,red blood cells shrink (lose volume);relative to the red blood cell cytoplasm,a 2 percent solution must be

Active carrier proteins use energy to carry passive carrier proteins into cells.

During ________ endocytosis,specific substances interact with proteins located in the plasma membrane of the cell.

The signaling molecules that interact with cell surface receptors cannot cross the plasma membrane and would generally be classified as large and/or________.

Channel proteins provide a means for large,________ molecules to move across the plasma membrane without an expenditure of energy.

For a cell to be a target for a particular hormone,it must usually

Channel proteins require energy for transporting molecules across the plasma membrane.

You observe a vesicle moving toward the plasma membrane from inside a cell.Once it reaches and fuses with the plasma membrane,you will most likely see an example of

Cells that experience high mechanical stress,like heart cells,typically connect to one another using a(n)________ junction,allowing the stress to be distributed to a larger area.