Ch. 3

Functions of the cell membrane include physical isolation of the cell from its surroundings, regulation of exchange, structural support, and which other function?

Communication between the cell and its environment

A double membrane droplet containing proteins along the center and an aqueous core...

Liposomes

Which of the following IS a function of membrane proteins?

-act as transport molecules for various solutes -anchor or stabilize the cell membrane -bind to ligands -regulate the passage of ions

Droplets of phospholipids containing a lipid core/center...

Micelles

If you were to throw many phospholipids into an aqueous solution, which of the following would you observe?

Phosphate heads and lipid tails would orient away from each other, with the phosphate heads facing either the extracellular or intracellular fluid and the tails facing each other.

Cell membrane properties vary considerably in different types of cells. What determines the specific properties of a cell membrane?

The relative amounts of proteins and lipids

cell lacks transmembrane proteins. Which loss of function would you expect to observe in this cell based on this observation?

an inability to transport ions, nutrients, and other substances across the membrane

the function of membrane proteins

-to combine with a carbohydrate, providing an immune response and/or cell recognition -to provide structural stability for the cell -to serve as a channel for the transport of molecules between extracellular and intracellular fluid -to allow for cell-cell communication

Define interstitial fluid, indicating whether it is inside or outside cells (intracellular or extracellular).

Interstitial fluid is extracellular fluid outside the circulatory system and the cells.

Which two fluid compartments make up the extracellular fluid?

Plasma and interstitial fluid

Two rows of phospholipds that forma sheet with tails facing each other and heads on either side facing the aqueous solution...

bilayer

Which of the following phrases best defines something that is hydrophobic? A substance that _______.

does not mix with water (water-fearing)

The lumen of a hollow organ such as the stomach is considered to be part of the ________ environment.

external

The watery medium that surrounds a cell is known as

extracellular fluid.

Cell membranes are mainly constructed from __________.

lipids and proteins

The space that is surrounded by the tissue wall of hollow organs is known as the

lumen.

Which structure is a lipid bilayer that controls which objects can leave or enter the cell?

plasma membrane

Which of the following is NOT a function of membrane proteins?

produce energy

Cell membranes are said to be

selectively permeable.

What is/are the major role(s) of the phospholipid bilayer?

the formation of a barrier that is selectively permeable to lipid-soluble molecules and to provide a framework for membrane proteins

________ proteins extend all the way across the cell membrane.

transmembrane