The Plasma Membrane - Gateway to the Cell 4/15/2017 The Plasma Membrane - Gateway to the Cell G. Podgorski, Biol. 1010

Photograph of a Cell Membrane The Plasma Membrane 4/15/2017 Photograph of a Cell Membrane G. Podgorski, Biol. 1010

Functions of Plasma Membrane The Plasma Membrane 4/15/2017 Functions of Plasma Membrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Contains the cytoplasm (fluid in cell) G. Podgorski, Biol. 1010

Structure of the Cell Membrane The Plasma Membrane 4/15/2017 Structure of the Cell Membrane G. Podgorski, Biol. 1010

Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT The Plasma Membrane Cell Membrane 4/15/2017 The cell membrane is made of 2 layers of phospholipids called the lipid bilayer Hydrophobic molecules pass easily; hydrophilic DO NOT G. Podgorski, Biol. 1010

The Plasma Membrane 4/15/2017 Types of Transport Across Cell Membranes Regulate transport in & out of cell (selectively permeable) G. Podgorski, Biol. 1010

Simple Diffusion Requires NO energy The Plasma Membrane 4/15/2017 Simple Diffusion Requires NO energy Molecules move from area of HIGH to LOW concentration G. Podgorski, Biol. 1010

The Plasma Membrane 4/15/2017 DIFFUSION Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY G. Podgorski, Biol. 1010

Diffusion of Liquids The Plasma Membrane 4/15/2017 G. Podgorski, Biol. 1010

Diffusion through a Membrane The Plasma Membrane 4/15/2017 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) G. Podgorski, Biol. 1010

Diffusion across a membrane Semipermeable membrane The Plasma Membrane 4/15/2017 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 G. Podgorski, Biol. 1010

Diffusion of H2O Across A Membrane The Plasma Membrane 4/15/2017 Diffusion of H2O Across A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration G. Podgorski, Biol. 1010

Aquaporins Water Channels Protein pores used during OSMOSIS The Plasma Membrane 4/15/2017 Aquaporins Water Channels Protein pores used during OSMOSIS WATER MOLECULES G. Podgorski, Biol. 1010

Cell in Isotonic Solution The Plasma Membrane 4/15/2017 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 _______________. G. Podgorski, Biol. 1010

Cell in Hypotonic Solution The Plasma Membrane 4/15/2017 Cell in Hypotonic Solution 10% NaCl 90% H2O CELL 20% NaCl 80% H2O What is the direction of water movement? G. Podgorski, Biol. 1010

Cell in Hypertonic Solution The Plasma Membrane 4/15/2017 Cell in Hypertonic Solution 15% NaCl 85% H2O ENVIRONMENT CELL 5% NaCl 95% H2O What is the direction of water movement? G. Podgorski, Biol. 1010

Cells in Solutions The Plasma Membrane 4/15/2017 G. Podgorski, Biol. 1010

NO NET MOVEMENT OF H2O (equal amounts entering & leaving) The Plasma Membrane 4/15/2017 Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS PLASMOLYSIS G. Podgorski, Biol. 1010

Cytolysis & Plasmolysis The Plasma Membrane 4/15/2017 Cytolysis & Plasmolysis Cytolysis Plasmolysis G. Podgorski, Biol. 1010

Osmosis in Red Blood Cells The Plasma Membrane 4/15/2017 Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic G. Podgorski, Biol. 1010

The Plasma Membrane 4/15/2017 G. Podgorski, Biol. 1010

Three Forms of Transport Across the Membrane The Plasma Membrane Three Forms of Transport Across the Membrane 4/15/2017 G. Podgorski, Biol. 1010

Passive Transport Simple Diffusion Doesn’t require energy The Plasma Membrane 4/15/2017 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. G. Podgorski, Biol. 1010

Facilitated diffusion The Plasma Membrane 4/15/2017 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. G. Podgorski, Biol. 1010

Proteins Are Critical to Membrane Function The Plasma Membrane 4/15/2017 Proteins Are Critical to Membrane Function G. Podgorski, Biol. 1010

Types of Transport Proteins The Plasma Membrane 4/15/2017 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 G. Podgorski, Biol. 1010

Facilitated Diffusion The Plasma Membrane 4/15/2017 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. G. Podgorski, Biol. 1010

Facilitated Diffusion The Plasma Membrane 4/15/2017 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

The Plasma Membrane 4/15/2017 Carrier Proteins Other carrier proteins change shape to move materials across the cell membrane G. Podgorski, Biol. 1010

Active Transport Requires energy or ATP The Plasma Membrane 4/15/2017 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient G. Podgorski, Biol. 1010

The Plasma Membrane 4/15/2017 G. Podgorski, Biol. 1010