Exercise 5A

The Cell: Transport and Membrane Permeability

There are two general categories of cellular transport mechanisms:

• Passive• Simple diffusion• Facilitated or protein mediated• Filtration• Osmosis

• Active• ATP driven solute pumps• Vesicular

• Endocytosis• Phagocytosis• Bulk-phase endocytocysis (pinocytosis)

• Phagocytosis

Types of transport

Rate of diffusion is influenced by:

• concentration• temperature• molecular or atomic weight of solute• density of solvent

• gases allow for the quickest• liquids are intermediate• solids allow for the slowest

Diffusion

Diffusion of dye in agar

KMnO2

Methyleneblue

Facilitated diffusion

Osmosis a.

Osmosis b.

What’s an “Osmometer”?

Normal erythrocytes in an isotonic solution

RBCs in hypertonic saline solution:crenation

Isotonic vs hypotonic

Normal RBCs:0.9% NaCl

Hemolysis:Distilled water

Active transport requires cellular energy

Exocytosis

Endocytosis (a.k.a. pinocytosis)

Phagocytosis: cellular eating

Active transport: AntiportThe sodium/potassium pump

Active transport: SymportThe sodium/glucose symporter

Transport Animations

http://personal.tmlp.com/Jimr57/textbook/chapter3/cmf1a.htm