Passive Transport This is going to show how cells transport substances in and out. 1

The cell membrane is trying to maintain HOMEOSTASIS or balance, by moving substances (solutes or solvents) across the membrane to where they are needed.

Substances Solute Solvent The substance being dissolved The substance that does the dissolving Ex. Sugar dissolving in H2O What is the solvent? What is the solute? Sugar Water

How does a membrane know which direction a substance needs to move? In most cases the substance tries to reach a state of equilibrium.

Equilibrium A stable or balanced system.

Equilibrium -EQUAL; the same - NOT EQUAL amount throughout

Concentration Gradient Notice how both examples are NOT in Equilibrium High Difference= High Concentration Gradient A concentration gradient represents a change in the concentration of a solute over a distance in a solution Low Difference = Low Concentration Gradient

Speed of movement based on Concentration Gradient Low Gradient High Gradient Small difference = moves slow Large difference = moves fast

Transport 1.) Passive Transport 2.) Active Transport Materials can move in and out of the cell in two ways: 1.) Passive Transport (no energy) 2.) Active Transport (uses energy)

Passive Transport Does not use Energy Goes with the Flow from High to Low (concentration) Movement DOWN the concentration gradient Ex: Diffusion Osmosis

Examples of Passive Transport Diffusion Movement from High to Low Concentration Osmosis Movement of WATER from High to Low Concentration through a membrane

Diffusion Does NOT use energy (goes by itself) Goes with the FLOW from HIGH to LOW

Diffusion of Liquids 13 The Plasma Membrane 12/3/2018 G. Podgorski, Biol. 1010 13

Proteins used for transport Remember? Proteins used for transport Some proteins act like channels or tunnels where materials can flow through by PASSIVE TRANSPORT This is called Facilitated Diffusion

Facilitated Diffusion (Diffusion with Help) Large molecules can diffuse across a membrane with the help of a protein

Facilitated Diffusion The Plasma Membrane 12/3/2018 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. 16 G. Podgorski, Biol. 1010 16

Facilitated Diffusion The Plasma Membrane 12/3/2018 Facilitated Diffusion Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side. 17 G. Podgorski, Biol. 1010 17

The Plasma Membrane 12/3/2018 Carrier Proteins Other carrier proteins change shape to move materials across the cell membrane 18 G. Podgorski, Biol. 1010 18