Passive Transport

Passive Transport Target: I will be able to describe the different types of passive transport, and, given a situation, analyze how molecules will move and what will happen to the cell. Passive Transport- The diffusion (movement/spreading) of substances across a membrane into available space without the use of energy. The movement of each molecule is random, but the diffusion of a population may be directional. Pg. 39

Passive Transport

Types of Passive Transport: 1. Diffusion: Movement of molecules across a selectively permeable membrane from areas of higher concentration to lower concentration until they reach equilibrium.

Rule of Diffusion: A substance will diffuse (move) down the concentration gradient- the region along which the density of a substance decreases

2. Facilitated diffusion: Movement of large particles from high to low concentration with the help of proteins. Transport Proteins: Proteins which move materials across a plasma membrane that would not otherwise be able to. One type is: Protein channels- which are pathways (corridors) that allow a specific molecule to cross the membrane.

3. Osmosis – Diffusion of water across a selectively permeable membrane from high to low concentration

Types of Osmosis: Isotonic Solution – When the concentration of water is the same on both sides of membrane. Cell is stable and will stay the same size

Hypertonic Solution – When there is more water inside the cell than outside Cell loses water to the outside environment Causes the cell to shrivel (shrink)

Hypotonic Solution – When there is more water outside the cell than the inside Water will enter the cell faster than it leaves Causes the cell to swell and lyse (burst) Osmosis

Diffusion and Osmosis Practice Examples: A cell with 40% solute is placed in a solution with 20% solute. What type of solution is this and what will happen to the cell? Hypotonic/The cell will swell as the water comes into it A cell with 60% solute is placed in a solution with 80% solute. What type of solution is this and what will happen to the cell?? Hypertonic/ The cell will shrink as the water goes out of it.

A cell with 15% solute is place in a solution with 15% solute A cell with 15% solute is place in a solution with 15% solute. What type of solution is this and what will happen to the cell? Isotonic/ The cell will stay the same size because there are equal amounts of water on both sides of the membrane.   There is 15% glucose inside and 5% glucose outside the cell. What will happen to the glucose? The glucose will move out of the cell

There is 7% water inside the cell and 7% water outside the cell There is 7% water inside the cell and 7% water outside the cell. What will happen to the water? No water will move into or out of the cell There is 56% water outside the cell and 40% water inside the cell. What will happen to the water? The water will move into the cell Summary:

No energy Needed Diffusion Facilitated Diffusion Osmosis Isotonic Hypertonic Hypotonic Draw pictures to help you remember each type of diffusion *Use a minimum of 4 colors Draw pictures to help you remember each type of solution and what happens to a cell placed in it. *Use a minimum of 4 colors Pg. 38