Cell Membrane Maintains homeostasis by regulating the movement of molecules in and out of the cell

Why is the plasma membrane described as “fluid mosaic”?

Fluid Mosaic Model Fluid Polar heads are orientated to the aqueous solution (inside and outside of cell) Non polar tails are orientated towards one another Mosaic Integral proteins are embedded to form a mosaic

Membrane Proteins Channel Proteins (transport) Carrier Proteins (transport) Receptor Proteins (signal transduction) Cell Recognition Proteins (glycoproteins) Enzymatic Proteins (internal active sites) Intercellular Joining (cell junctions) Attachment for Cytoskeleton

Membrane Permeability Impermeable Permeable Differentially/Selectively Permeable

Terms to know Osmotic pressure Turgor Pressure Tonicity Isotonic Hypotonic Hypertonic Plasmolysis Creanation

Methods of Transport Across The Cell Membrane Passive Transport

Molecules Using Diffusion Lipids (steroids) O2 & CO2 Through phospholipids bilayer

Factors Affecting Rates of Diffusion Temperature increase Increased concentration gradient Increased membrane permeability Smaller molecule size

Osmosis Diffusion of water through a semi permeable membrane (channel proteins)

Problems to Solve Which side is hypertonic? Which side is hypotonic? Which way will water move in 30 minutes? After 30 minutes which side has a higher concentration? If the membrane is impermeable to salt but permeable to glucose describe the movement of solutes and water after 2 hours.

This happens in plants….what is it?

Facilitated Transport/Diffusion Movement of molecules along the concentration gradient with the aid of carrier proteins Example: amino acids, glucose

Active Transport Movement of molecules against the concentration gradient using carrier proteins and ATP Example: Na+, K+ and iodine

Types of Active Transport for Macromolecules

Types of Active Transport for Macromolecules

Animation Review