Diffusion and osmosis

Types of Cellular Transport Passive Transport cell doesn’t use energy Diffusion Facilitated Diffusion Osmosis Active Transport cell does use energy Protein Pumps Endocytosis Exocytosis high low Weeee!!! high low This is gonna be hard work!!

Bacon Frying… What do you smell? Why do you smell this?

Bacon Frying… Fat droplets are released into the air steam coming off of the bacon Causes the fat droplets (particles) to collide and disperse. In science terms… DIFFUSION IS OCCURING!  The bacon fat droplets (particles) diffuse from the area of high concentration (directly above the frying pan), to areas of low concentration (the room) Continues until equilibrium is reached Particles equally distributed throughout the space (room)

Diffusion Diffusion - Defined as the movement of particles from areas of high concentration to areas of low concentration (down the concentration gradient) Particles spread out Ex: Solute = perfume Solvent = the air Low Solute Concentration An example of diffusion in the air and also in an agar dish are good to go over here. High Solute Concentration

Diffusion

Diffusion rate (how fast it occurs) depends on: 1. Size- smaller molecules move more easily 2. Concentration- high concentration = faster spread Ex: The more bacon you have (=more fat droplets released), the faster the smell will spread throughout the room 3. Temperature- high temps speed up the process Which will cause the smell to disperse faster? Cold bacon in a frying pan and the stove is OFF OR Bacon in a frying pan and the stove in ON

What is a semi-permeable membrane? A membrane that allows certain molecules to pass through it by diffusion or osmosis Think about a Ping-Pong net.. Which would pass through?

Osmosis Diffusion that involves water. Movement of water across a semi-permeable membrane

Cell membranes are semi-permeable Water and some gases move through the membrane easily, while larger molecules like proteins and sugars do not. Cells must regulate- molecules move from internal environment to external environment (and vice versa) so that both environments have equal concentrations. Animation: How Osmosis Works

Why do your fingers “shrivel–up” when you are in the water? Osmosis Diffusion that involves water. Movement of water across a semi-permeable membrane Water moves from areas of low solute to areas of high solute Why do your fingers “shrivel–up” when you are in the water?

Effects of Osmosis on Life Osmosis- diffusion of water through a selectively permeable membrane. There are 3 types of solutions (=Tonicity) 1.) Isotonic 2.) Hypertonic 3.) Hypotonic

WATCH VIDEO OF BLOOD IN AN ISOTONIC SOLUTION Solutions that contain the same concentration of solutes as the cytoplasm are called isotonic (or normal saline) solutions. There is no net movement of water either into or out of the cell. Cells maintain their normal shape.

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic Solution Isotonic The concentration of solutes in the external solution is equal to the concentration of solutes inside the cell. Result Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

WATCH VIDEO OF NORMAL RBCs SUBJECTED TO A HYPERTONIC SOLUTION A hypertonic solution is a solution that contains more solutes than the cytoplasm of the cell. (hyper) Has less water than the cell and water moves out of the cell. The cells shrink.

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis/crenation)!

WATCH VIDEO OF CRENATED RBCs SUBJECTED TO A HYPOTONIC SOLUTION A hypotonic solution contains less solute (thus, more water) than the cytoplasm of the cells. The water will move into the cells resulting in the swelling and lysis of the cells. 

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

Let’s take a closer look! http://www.coolschool.ca/lor/BI12/unit4/ U04L06/rbc.html

B C A What type of solution are these cells in? Hypertonic Isotonic Hypotonic

Tonicity Used to compare different solutions Hypertonic- higher solute concentration relative to another *think hyperactive Hypotonic- lower solute concentration relative to another *think hypothermia Isotonic- equal solute concentrations between two solutions

Cell in Isotonic Solution The Plasma Membrane 4/15/2017 Cell in Isotonic Solution ENVIRONMENT 10% NaCL 90% H2O CELL NO NET MOVEMENT 10% NaCL 90% H2O The cell is at _______________. equilibrium What is the direction of water movement? 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

What Happens to Blood Cells?