Cell Transport

What direction do molecules move during facilitated diffusion?

During facilitated diffusion molecules move through protein doorways from areas of HIGH concentration to LOW concentration.

What is the end result of diffusion?

Equilibrium -- a relatively equal distribution of particles in an area

Give two examples of molecules that utilize facilitated diffusion (move through protein "doorways" in the membrane)

Glucose and amino acids (while not large, these molecules are not small enough to slip between the phospholipids of the cell membrane)

What is endocytosis?

Molecules (usually large in size ) are taken into the cell. The cell membrane surrounds & engulfs the object packaging it within a vesicle.

Which molecules are small enough for simple diffusion ( squeezing between the phospholipids of the cell membrane)?

Oxygen, water, carbon dioxide

Is facilitated diffusion active or passive transport?

Passive Transport --- no ATP needed & molecules move DOWN the concentration gradient ( from high concentration to low concentration)

Simple diffusion

Small molecules squeeze between the phospholipid bilayer to move from an area of HIGH concentration to LOW concentration. No ATP is needed

Exocytosis

The REMOVAL of materials out of the cell by the fusing of a vesicle (that contains the particle to be removed) with the cell membrane

What cell structure regulates the movement of material into and out of the cell?

The cell membrane

Describe the structure of the cell membrane.

The cell membrane is a phospholipid bilayer (2 layers of phospholipids) with protein embedded

What is osmosis?

The diffusion of water. Water moves from high concentration to low concentration without the use of ATP

What is active transport?

The movement of molecules AGAINST the concentration gradient -----from low concentration to high concentration ** ATP is required!

Passive Transport

The movement of molecules DOWN the concentration gradient (From a region of HIGH concentration to LOW concentration) No ATP is needed Ex: simple diffusion facilitated diffusion osmosis

What causes molecules to diffuse?

The particles of matter are in constant, random motion. Collisions between crowded molecules eventually spread molecules out (so that they move from crowded regions to less crowded regions)

What is facilitated diffusion?

The use of protein "doorways" in the membrane to help molecules move into or out of the cell

What does the word " facilitate " mean?

To help or assist

Can protein "doorways" be used for active transport?

Yes!!! Molecules can be moved passively ( from high to low with no ATP) or actively (from low to high with the use of ATP) through membrane proteins