Cells: Membrane Transport

Cell Membrane Structure Fig. 7-2 Cell Membrane Structure WATER Hydrophilic head Figure 7.2 Phospholipid bilayer (cross section) Hydrophobic tail WATER

Cellular Physiology: Membrane Transport Two Types of Transport: Passive and Active 1. Passive transport Does not require energy to transport across the membrane Slide 3.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Passive Transport Processes Simple diffusion Particles tend to distribute themselves evenly within a solution Movement is from high concentration to low concentration, or down a concentration gradient Figure 3.8 Slide 3.23 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Passive Transport Processes Facilitated diffusion Allows lipid insoluble substances (i.e. glucose) to pass through using a protein channel from high to low concentration

Passive Transport Processes Osmosis – simple diffusion of water Osmosis & Diffusion Animation Slide 3.24b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cellular Physiology: Membrane Transport Two Types of Transport 2. Active transport Requires energy to transport across the membrane Solutes move from low to high concentration or against the concentration gradient Slide 3.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Active Transport Processes Bulk transport Exocytosis Moves materials out of the cell Material is carried in a vacuole Vacuole migrates to cell membrane Vacuole combines with cell membrane Material is emptied to the outside of the cell Slide 3.29a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Active Transport Processes Figure 3.11 Slide 3.29b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Active Transport Processes Bulk transport Endocytosis Process of taking material into the cell by means of infoldings, or pockets, of the cell membrane Slide 3.30a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Active Transport Processes Bulk transport Types of endocytosis Phagocytosis – cell eating – brings in large particles within a food vacuole Pinocytosis – cell drinking – cells taking up liquid from the surrounding environment Slide 3.30a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Active Transport Processes Figure 3.12 Slide 3.30b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Effects of Osmosis on Cells Type of Solution Animal Cell Plant Cell Isotonic: The concentration of solutes (salt) is the same inside and outside the cell. Water moves equally into and out of the cell

Effects of Osmosis on Cells Type of Solution Animal Cell Plant Cell Hypertonic: Solution has a higher solute (salt) concentration than the cell. Water leaves the cell and it loses turgor pressure And causes the cell to shrink

Effects of Osmosis on Cells Type of Solution Animal Cell Plant Cell Hypotonic: Solution has a lower solute (salt) concentration than the cell. Water enters the cell and Pushes against The cell wall Increasing the turgor pressure Causing the cell to swell and possibly burst

What type of solution do you think this red blood cell was placed in? A B C

What type of solution do you think this red blood cell was placed in? Hypotonic! A B C