copyright cmassengale The Plasma Membrane 9/17/2018 Cell Transport How to modify this powerpoint: -simple diffusion vs. facilitated diffusion -cell membrane stuff -selectively permeable membrane -define equilibrium and concentration gradient? -define isotonic, hypertonic, hypotonic -active transport Use jenn nemec’s chart to go along with it copyright cmassengale G. Podgorski, Biol. 1010

Check Your Understanding At the end of today’s lesson, you should be able to answer the following questions: What are the parts of the cell membrane and what do they do? What is the “Fluid Mosaic Model?” Describe the processes of diffusion, osmosis, facilitated diffusion, and active transport.

copyright cmassengale Cell Membrane Regulates passage of materials into and out of the cell Parts of the membrane: A) lipid bilayer (2 layers) B) proteins C) cholesterol D) carbohydrate chains copyright cmassengale

copyright cmassengale Lipid Bilayer Made of 2 sheets of phospholipids, a type of lipid with a head and 2 tails Hydrophilic (water loving) head Hydrophobic (water fearing) tail copyright cmassengale

Why do the phospholipids arrange themselves in a bilayer? copyright cmassengale

Membrane Proteins: Act as channels for large particles to enter and leave the cell Fluid-Mosaic Model: describes the flexibility of the lipid bilayer with a mosaic of proteins and other molecules ..\..\..\Downloaded Videos\Fluid mosiac model.avi

Carbohydrate Chains Recognize parts of molecules to determine what molecules can be brought into the cell Can be attached to proteins or phospholipids Lock and Key Fit!

Label the Parts of the Membrane! Outside cell Inside cell Phospholipid Protein Carbohydrate Chain

Function of the Cell Membrane Regulates what enters and leaves the cell Provides protection and support

Random Transition…AHHHH! This may seem completely rando…but I promise the dots will connect later!

Concentration In a solution, the concentration is the mass of solute in a given volume of solution A difference in concentration over a distance is called a concentration gradient

The Plasma Membrane 9/17/2018 Simple Diffusion Description: Molecules move from area of HIGH to LOW concentration This means they are going DOWN the CONCENTRATION GRADIENT PASSIVE Process (no energy required) G. Podgorski, Biol. 1010

..\..\..\Downloaded Videos\Diffusion.avi The Plasma Membrane 9/17/2018 ..\..\..\Downloaded Videos\Diffusion.avi G. Podgorski, Biol. 1010

Simple Diffusion of a Solute Across a Membrane copyright cmassengale

Can all solutes cross the membrane by simple diffusion? NO! The membrane is selectively permeable, this means only certain solutes (typically small ones) can pass across by simple diffusion The solution? – Channel Proteins! copyright cmassengale

Facilitated Diffusion Description: Diffusion of certain molecules through a selectively permeable membrane, made possible by protein channels PASSIVE Process DOWN gradient ..\..\..\Downloaded Videos\facilitated diffusion.avi

The Plasma Membrane 9/17/2018 Osmosis Description: Diffusion of WATER across a selectively permeable membrane PASSIVE process DOWN GRADIENT (that is, WATER moves down its gradient) ..\..\..\Downloaded Videos\Osmosis.avi G. Podgorski, Biol. 1010

Cell in Isotonic Solution The Plasma Membrane 9/17/2018 Cell in Isotonic Solution ENVIRONMENT 10% solute 90% water Solution outside the cell has the SAME solute (and water) concentration as the cell itself CELL 10% solute 90% water What is the direction of water movement? The cell is at EQUILIBRIUM. G. Podgorski, Biol. 1010

Cell in Hypotonic Solution The Plasma Membrane 9/17/2018 Cell in Hypotonic Solution 10% solute 90% water ENVIRONMENT Solution outside the cell has a LOWER solute (HIGHER water) concentration than the cell itself CELL 20% solute 80% water What is the direction of water movement? G. Podgorski, Biol. 1010

Cell in Hypertonic Solution The Plasma Membrane 9/17/2018 Cell in Hypertonic Solution 15% solute 85% water ENVIRONMENT Solution outside the cell has a HIGHER solute (LOWER water) concentration than the cell itself CELL 5% solute 95% water What is the direction of water movement? G. Podgorski, Biol. 1010

NO NET MOVEMENT OF H2O (equal amounts entering & leaving) The Plasma Membrane 9/17/2018 Hypertonic Solution Isotonic Solution Hypotonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) Cell Shrinking Cell Bursting ..\..\..\Downloaded Videos\Red Blood Cells in Hypotonic Solution.avi ..\..\..\Downloaded Videos\Onion Cells Plasmolysis.avi ..\..\..\Downloaded Videos\Red Blood Cells in a Hypertonic Solution.avi G. Podgorski, Biol. 1010

Osmosis in Red Blood Cells The Plasma Membrane 9/17/2018 Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic copyright cmassengale G. Podgorski, Biol. 1010

Osmosis in Plant Cells

Active Transport Description: Movement of materials from LOW to HIGH concentration ACTIVE process (uses energy) UP Concentration Gradient

Active Transport Molecular Pumps Molecular pumps are membrane proteins that use energy from ATP to move molecules across cell membranes. (Each pump moves one type of molecule) ATP ..\..\..\Downloaded Videos\Active Transport.avi

Endocytosis vs. Exocytosis Endocytosis: taking large amounts of material into the cell Exocytosis: sending large amounts of material out of the cell copyright cmassengale

Endocytosis: Phagocytosis & Pinocytosis Phagocytosis: The membrane folds to enclose solid particle (cell eating) Pinocytosis: The membrane folds to enclose liquid with dissolved materials (cell drinking)

copyright cmassengale In endocytosis, the membrane pinches in to form a vesicle The vesicle may later join with a lysosome so that particles can be “digested” Vesicles copyright cmassengale

Exocytosis 1 Products of the ER are packaged in vesicles at the Golgi and released at the cell membrane. ..\..\..\Downloaded Videos\Endocytosis & Exocytosis.avi

Cell Membrane and Homeostasis Refresher from Characteristics of Life…what is homeostasis? How does the cell membrane help organisms to maintain homeostasis?