10/19/2012

1

Cellular Transport

Passive Transport

�Movement of particles across the plasma

membrane without using energy.

Three Modes of Passive Transport

�Diffusion �Facilitated Diffusion �Osmosis

Diffusion in a Cell

�Movement of particles from an area of

high concentration to an area of lower concentration

Carrier ProteinsChannel Proteins

Facilitated Diffusion

�Movement of materials across the

plasma membrane using proteins.

Cellular Structure and FunctionOsmosis

�Diffusion of water across a selectively

permeable membrane

Three Types of Solutions

�Isotonic

�Hypotonic

�Hypertonic

10/19/2012

2

Cellular Structure and Function

Blood CellPlant Cell

Isotonic Solution

�Water and dissolved substances diffuse

into and out of the cell at the same rate.

�Cell stays the same size.

11,397x

Blood Cell

Hypotonic Solution

�Solute concentration is higher inside the

cell.

�Water diffuses into the cell and swells.

Plant Cell

13,000x

Plant Cell

Hypertonic Solution�Solute concentration is higher outside

the cell.�Water diffuses out of the cell and shrinks.

Blood Cell

13,000x

Active Transport

�Movement of particles across the plasma

membrane using energy.

Active Transport Using Carrier Proteins

Endocytosis

�Process by which the

cell surrounds and

takes particles into the

cell

Exocytosis

�Secretion of material

out of the plasma

membrane

Other ways of Active Transport