Types of Transport Across Cell Membranes The Plasma Membrane 5/22/2019 Types of Transport Across Cell Membranes copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Simple Diffusion Requires NO energy Molecules move from area of HIGH to LOW concentration copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 DIFFUSION Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural ENERGY copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Diffusion of Liquids copyright cmassengale G. Podgorski, Biol. 1010

Diffusion through a Membrane The Plasma Membrane 5/22/2019 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) copyright cmassengale G. Podgorski, Biol. 1010

Concentration Gradient

Diffusion across a membrane Semipermeable membrane The Plasma Membrane 5/22/2019 Osmosis Diffusion across a membrane Diffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute) Semipermeable membrane copyright cmassengale G. Podgorski, Biol. 1010

Diffusion of H2O Across A Membrane The Plasma Membrane 5/22/2019 Diffusion of H2O Across A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration copyright cmassengale G. Podgorski, Biol. 1010

Cell in Isotonic Solution The Plasma Membrane 5/22/2019 Cell in Isotonic Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________. copyright cmassengale G. Podgorski, Biol. 1010

Cell in Hypotonic Solution The Plasma Membrane 5/22/2019 Cell in Hypotonic Solution 10% NaCL 90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement? copyright cmassengale G. Podgorski, Biol. 1010

Cell in Hypertonic Solution The Plasma Membrane 5/22/2019 Cell in Hypertonic Solution 15% NaCL 85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement? copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Cells in Solutions copyright cmassengale G. Podgorski, Biol. 1010

Osmosis in Red Blood Cells The Plasma Membrane 5/22/2019 Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic copyright cmassengale G. Podgorski, Biol. 1010

What Happens to Blood Cells? copyright cmassengale

Three Forms of Transport Across the Membrane The Plasma Membrane Three Forms of Transport Across the Membrane 5/22/2019 copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Passive Transport Simple Diffusion Doesn’t require energy Moves high to low concentration Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out. copyright cmassengale G. Podgorski, Biol. 1010

Facilitated diffusion The Plasma Membrane 5/22/2019 Passive Transport Facilitated diffusion Doesn’t require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell. copyright cmassengale G. Podgorski, Biol. 1010

Proteins Are Critical to Membrane Function The Plasma Membrane 5/22/2019 Proteins Are Critical to Membrane Function copyright cmassengale G. Podgorski, Biol. 1010

Types of Transport Proteins The Plasma Membrane 5/22/2019 Types of Transport Proteins Channel proteins are embedded in the cell membrane & have a pore for materials to cross Carrier proteins can change shape to move material from one side of the membrane to the other copyright cmassengale G. Podgorski, Biol. 1010

Facilitated Diffusion The Plasma Membrane 5/22/2019 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. copyright cmassengale G. Podgorski, Biol. 1010

Facilitated Diffusion The Plasma Membrane 5/22/2019 Facilitated Diffusion Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side. G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Carrier Proteins Other carrier proteins change shape to move materials across the cell membrane copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Active transport Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients. Called Na+-K+ Pump copyright cmassengale G. Podgorski, Biol. 1010

Sodium-Potassium Pump The Plasma Membrane 5/22/2019 Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential copyright cmassengale G. Podgorski, Biol. 1010

Moving the “Big Stuff” Exocytosis- moving things out. The Plasma Membrane Moving the “Big Stuff” 5/22/2019 Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many hormones are secreted and how nerve cells communicate with one another. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane Exocytosis 5/22/2019 Exocytic vesicle immediately after fusion with plasma membrane. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane Moving the “Big Stuff” 5/22/2019 Large molecules move materials into the cell by one of three forms of endocytosis. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane Pinocytosis 5/22/2019 Most common form of endocytosis. Takes in dissolved molecules as a vesicle. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Pinocytosis Cell forms an invagination Materials dissolve in water to be brought into cell Called “Cell Drinking” copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane Example of Pinocytosis 5/22/2019 mature transport vesicle pinocytic vesicles forming copyright cmassengale Transport across a capillary cell (blue). G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Receptor-Mediated Endocytosis Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane Receptor-Mediated Endocytosis 5/22/2019 copyright cmassengale G. Podgorski, Biol. 1010

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copyright cmassengale The Plasma Membrane 5/22/2019 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating” copyright cmassengale G. Podgorski, Biol. 1010

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copyright cmassengale The Plasma Membrane Phagocytosis About to Occur 5/22/2019 copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue) copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/22/2019 Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell copyright cmassengale Cell environment G. Podgorski, Biol. 1010