HOW DO MATERIALS MOVE IN AND OUT OF CELLS? Chapter 2.7 HOW DO MATERIALS MOVE IN AND OUT OF CELLS?

Which part of cell controls the movement of materials in and out of cell? Cell membrane

Diffusion DIFFUSION- is a movement of material from an area where molecules are crowded to areas where they are less crowded (or from high concentration to low concentration).

Osmosis OSMOSIS- is the movement of water through the cell membrane. Water usually moves through a cell membrane to an area with more solutes (water follows salt, sugar, and other materials).

OSMOSIS: Selective permeability- The cell membrane allows some substances to pass through and some not.

How Osmosis Works? The membrane is permeable to water, but not permeable to sugar. Water will keep moving across the membrane until the equilibrium (balance) is reached.

Terms for solution: ISOTONIC solution = same concentration HYPERTONIC solution = more concentrated solution (has more solutes) HYPOTONIC solution = less concentrated solution (has less solutes) Solutes = sugar, salt, nutrients, proteins

Animations http://www.zo.utexas.edu/faculty/sjasper/images/diffusion.swf http://physioweb.med.uvm.edu/diffusion/

Passive Transport PASSIVE TRANSPORT- movement of materials through a membrane without the use of energy.

Active transport ACTIVE TRANSPORT- movement of materials through a cell membrane with the use of energy. Sometimes when molecules need to move to an area with a lot molecules, they will need to use energy for the movement. It’s the opposite of diffusion.

Active transport animation http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

Checking concepts: Where do most molecules move to?

What is the difference between diffusion and osmosis?

What is passive transport?

What would happen if water constantly entered a cell, and none left it?

Will a teaspoon of salt dissolve more quickly in a glass of fresh water or a glass of salt water? Explain.

Why might the smell of freshly baked bread eventually fill an entire house?

Fill in blanks: 1. The movement of molecules from crowded areas to less crowded areas is called __________________. 2. The movement of water through a membrane is called ____________________. 3. The ____________________ controls what molecules pass in and out of a cell. 4. Many substances dissolve in _______________ before entering a cell. 5. Active transport requires _______________.