Membrane Structure

Membrane StructureReview: Phospholipid structure and properties

*amphipathic

Membrane Models:

1935 Today

Cell biology at work: membranes “uncovered”

*Membranes are fluid

Membranes are fluid

*Some functions of membrane proteins:

Transport

Enzymatic activity

Signal transduction

Intercellular junction

Cell recognition

Anchors

Membrane Transport

*Channel protein *Carrier protein

Traffic across membranes

*Passive transport

*Active transport

Passive transport

*Selective permeability

*Diffusion

Osmosis is the passive transport of waterWhen comparing two solutions:

*hypertonic

*hypotonic

*isotonic

Passive transportFacilitated diffusion

Channel proteins and carrier proteins

*Each cell membrane has characteristic set of carrier

proteins

*Active transport

Example: sodium-potassium pump

Electrogenic pump:

*Some ion pumps generate voltage across membranes

*Voltage*Membrane potential