Movement across cell membranes Ch. 7-3

1. Movement across cell membranes Ch. 7-3 Types of Movement Diffusion • Materials are moved across the cell membrane in various ways • Movement (mov’t) of molecules (molec.) from an area of higher concentration (conc.) to a lower conc.

2. Movement across cell membranes Ch. 7-3 Passive transport Active transport • Mov’t of molec. from an area of higher conc. to a lower conc. • does NOT require energy • Mov’t of molec. against the conc. Gradient from an area of lower conc. to an area of higher conc. • Occurs with the help of protein channels embedded in the membrane • REQUIRES energy

3. Movement across cell membranes Ch. 7-3 Osmosis The diffusion of WATER from an area of higher conc. to an area of lower conc.

4. Movement across cell membranes Ch. 7-3 Effects of osmosis on cells The solution that cells are in are classified 3 ways. Each type affects the direction WATER flows.

5. Clips for osmosis • http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

6. Movement across cell membranes Ch. 7-3 1. Isotonic“same strength” 2. Hypertonic“above strength” 3. Hypotonic“ below strength” • The conc. of molec. are equal on both sides of the membrane. Water moves is both directions • The conc. of molec. are greater outside of the cell than inside. Water moves out of cell! • The conc. of molec. are greater inside the cell than outside. Water moves in the cell !

7. Movement across cell membranes Ch. 7-3 Endocytosis • process of taking nutrients into the cell by the cell membrane forming a pocket

8. Movement across cell membranes Ch. 7-3 Phagocytosisphage= to eat • “cell eating” extentions of the cytoplasm surround a particle and package it w/in a food vacuole • Cells engulf large particles

9. Movement across cell membranes Ch. 7-3 Pinocytosispino= to drink • Cells take up liquid from the surrounding environment • Forms vacuoles w/in the cell

10. Movement across cell membranes Ch. 7-3 Exocytosis • Cells releasing waste products, forcing contents out of the cell