Membranes and Transport

Important Terms

Solvent a solution capable of dissolving other substances

Solute a minor component dissolved in solvent

The Cell Membrane

The cell membrane is in charge of what gets in to and out of the cell Import nutrients Export molecules and waste

If good stuff couldn’t get in and bad stuff couldn’t get out, the cell would die

Fluid mosaic model

The cell membrane is made up of phospholipid bilayer (‘2 layers’)

This barrier allows certain things to pass through it (eg. water, oxygen) but stops others (eg. ions, macromolecules) and is ‘semi-permeable’

=

O2

O2

H2O

H2O

Na+ Na+

extracellular

intracellular

hydrophilic

hydrophobic

Fluid mosaic model

This semi-liquid ‘sea’ of lipids has proteins floating within it that help move things across the membrane

**I will draw the important parts on the board with you...**

FYI

FYI

FYI

There are 2 types of membrane transport:1. Passive transport

Diffusion Facilitated diffusion Osmosis

2. Active transport Protein pumps Endo/Exocytosis

Transport happens through phospholipid bilayer or membrane proteins only

Back to membrane transport...

NO energy needed(it just happens!)

Energy needed(otherwise it won’t happen)

Important Terms

Permeable allowing material through

Impermeable not allowing material through

Semi-permeable allowing some material through but not others

Diffusion

Movement of molecules from an area of high concentration to an area of low concentration

Osmosis

Osmosis is the movement of water molecules through a semi-permeable membrane into a region of higher solute concentration