The Cell Membrane

1. Physical barrier Separates inside of the cell (cytoplasm) from the outside (extracellular fluid). 2. Controls passage of materials Entry/exit of molecules and substances 3. Senses changes Contains receptors 4. Supports structure Attached to microfilaments.

Fluid mosaic model

molecules constantly moving

made of different types of molecules

a phospholipid bilayer Cholesterol Proteins

hydrophilic

hydrophobic

Outside of the layer

Inside of the layer

Uses the cells energy

does not involve using the cells energy

facilitated transport Vascular transport

simple diffusion Osmosis Facilitated transport

The process of particles spreading out results in an even distribution of gases and liquids

The diffusion of a solvent through a differentially permeable membrane resulting in a balanced concentration.

the movement of substances across the cell membrane in membranous sacs called vesicles

Transport through proteins

• ) specific substance binds to a binding site • ) protein changes shape and opens up • ) substance is released on the opposite side

entering the cell

exiting the cell

solid particles

liquid particles

along (high->low)

against (low->high)