Passive Transport

Healthy Cell 70% water 15% protein 10% fat 4% DNA and other materials 1% carbohydrate

How do cells get what they need? Passively – certain materials go in and out of the cell through the cell membrane with out using any energy Actively – energy is required to bring nutrients into the cell and energy is required to eliminate wastes from the cell

Two Methods cells use to get what they need Passive Transport – does not require energy Active Transport – does require energy

Types of Passive Transport Simple diffusion Facilitated diffusion Osmosis

Simple diffusion Simple Diffusion – When substances (particles or molecules) move from a an area of high concentration to an area of low concentration across a selective semi permeable membrane without any trouble or interference move from a an area of high concentration to an area of low concentration

What is a selectively permeable membrane? It let’s certain materials in or out of the cell but not others. It’s particular!

Facilitated diffusion Molecules that have a certain chemical make up look for a doorway or channel so they can get in or out of the cell without using energy These doorway channels are selective in what they let in and out of the cell

Osmosis The diffusion of water only The rate of diffusion of water is dependent on temperature, pressure, and the concentration of other substances like salt

Diffusion and Osmosis

Equilibrium is the goal of Passive Transport When the concentration of the diffused particles is the same on both sides of the semi permeable membrane The inside of the cell has the same concentration of diffused materials as the outside of the cell

Homeostasis

Questions…. Why is it important to keep the right balances of water, oxygen, protein, carbohydrate and fats outside the cell? How do we do this?

Active Transport

What does a cell do if…. It is in equilibrium but it still needs more diffusible materials? It needs nutrients that are too large to passively go through the cell membrane? It needs to get rid of wastes that are too large to passively leave the cell?

Active transport When substances move from an area of low concentration to high concentration This does require energy! ATP is the carrier molecule that provides the energy necessary for active transport to occur Draw this!

Active transport: requires energy!

Endocytosis When the cell needs particles that are too large and cannot pass through the semi permeable membrane – endocytosis

Exocytosis When the cell wants to get rid of particles that are too large to pass through the semi permeable membrane - exocytosis

Active Transport