phospholipid bilayer

A double-layered sheet at the core of nearly all cell membranes.

These structures form by themselves when certain kinds of lipids are dissolved in water. 

Concentration

The mass of solute in a given volume of solution, or mass/volume.

For example, if you dissolved 12 grams of salt in 3 liters of water, the                         of the solution would be 12 g/3 L, or 4 g/L (grams per liter). 

diffusion

When molecules tend to move from an area where they are more concentrated to an area where they are less concentrated.

This process causes many substances to move across a cell membrane but does not require the cell to use energy. 

selectively

permeable

Because some substances can pass across a biological membrane and others cannot it is called                                             .

osmosis

A process that allows water molecules to pass easily through most biological membranes.

The diffusion of water through a selectively permeable membrane. 

FACILITATED

DIFFUSION

active transport

When material moves from an area of lower concentration to an area of greater concentration at the cost of extra cellular energy; or when large amounts of substances are moved into or out of the cell

endocytosis

It is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane.

phagocytosis

When large, solid particles are taken into the cell by endocytosis.

The removal of large amounts of material from a cell; the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell. 

What processes

are made possible

by the cell membrane?

• Diffusion
• Osmosis
• Facilitated Diffusion
• Active Transport 

How does

diffusion

affect cells?

It causes many substances to move across a cell membrane but doesn't require the cell to use energy.

Describe

how water moves

during osmosis.

Although water molecules move in both directions across the membrane, there is a net movement of water into the compartment containing the concentrationed sugar solution.  That means more water is moving into this compartment than out of it.

Why? Water, like other substances, tends to diffuse from a region where it is highly concentrated to one where it is less concentrated.   

What is

the basic structure

of a cell membrane?

A border that seperates the cell from its surroundings. 

The core of nearly all cell membranes is a double-layered sheet called a lipid bilayer.  Proteins & carbohydrate chains are also embedded within the cell membrane.

Pinocytosis

The process in which a cell engulfs large amounts of a liquid via endocytosis.