“Materials move across the cell’s membranes” Section 2.3

Do Now!!  What is the purpose of the cell membrane? What would happen if we didn’t have cell membranes? What goes in and out of our cells?

Objectives To explain the different functions of the macromolecules in the plasma membrane. To understand the process of diffusion. To compare and contrast active and passive transport.

The Cell Membrane Called a “Fluid Mosaic Model” Proteins and other components embedded like a mosaic http://www.youtube.com/watch?v= Qqsf_UJcfBc

Membrane Components Phospholipids: Give the general structure of the membrane

Please draw a phospholipid! Draw a phospholipid and label its parts!

Membrane Components Proteins: Allow bigger substances to pass through Provide structure: Microtubules and microfilaments (cytoskeleton)

Membrane Components Cholesterol: helps maintain structure of phospholipids prevents the tails from sticking together

Membrane Components Carbohydrates: receptors that send and receive signals from other cells Attached to glycolipids and glycoproteins

Types of Transport across a cell membrane Passive Transport Active Transport Vesicular Transport

Passive Transport Does NOT require energy Molecules go from an area of high concentration to an area of low concentration “Go with the flow”

3 Types of Passive Transport Diffusion Facilitated Diffusion Osmosis

What is diffusion? Movement of particles from area where there are many to area where there are fewer From high to low concentration

What is diffusion? Molecules move from high concentration to low concentration to create DYNAMIC EQUILIBRIUM Concentrations are the same in all areas

Affected By… Heat- higher temp increases rate State of Matter Solid- slow Liquid- faster Gas- fastest Size and Concentration Bigger= slower More concentration = faster

Do Now!!  Explain what happens when you put a sugar cube in your tea in regards to diffusion.

Objectives Explain facilitated diffusion Define solute, solvent and solution Identify different types of solutions Participate in a diffusion dialysis tubing demo

Explain what’s happening…

Facilitated Diffusion Certain molecules need a “helper” or “facilitator” to allow them to cross the membrane when they are too big.

Osmosis The flow of WATER from a high concentration to a low concentration

Solution A mixture in which you cannot separate the components (ex: iced tea) solute: the substance being dissolved Ex: iced tea powder solvent: The substance doing the dissolving Ex: water

Isotonic Solutions Blood Cell Plant Cell Same amount of solute inside the membrane as there is outside. Cell in this solution: NOTHING  Blood Cell Plant Cell

HYPERtonic Solutions More solute, less water on outside of the membrane Cell in this solution: shrinks/shrivels 

HYPOtonic Solutions Less solute, more water on outside of membrane Effect: cell swells or bursts! /

Identify the type of solution! Cell in ________ Solution Cell in ________ Solution Cell in ________ Solution H2O H2O H2O

Answer key! Cell in hypotonic Solution Cell in isotonic Solution Cell in hypertonic Solution H2O H2O H2O

Let’s try another… For the following examples: Which way is the water moving? What kind of cell solution (outside)? What is going to happen to the cells? A. B. C. 12% Salt 9% Salt 28% Salt 18% Salt 2% Salt 3% Salt

Real life osmosis situations A salt water fish is put into a freshwater aquarium. What type of solution is the freshwater? What is going to happen to the cells of the fish?

Real life osmosis examples A patient is given an IV, which contains the perfect balance of saline What type of solution is in the IV? What is going to happen to the cells of the human?

Real life osmosis examples Your garden is infested with slugs so you go around pouring salt on them What type of solution is this salt? What is going to happen to the cells of the slug? (don’t do this to the poor slugs )

Active Transport When molecules move from a low concentration to a high concentration and must use ENERGY. Example- Sodium Potassium Pump http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chap ter2/animation__how_the_sodium_potassium_ pump_works.html

Vesicular Transport Sometimes things enter and exit the cell by forming vesicles. For example… Endocytosis: When cells absorb molecules by engulfing them. (like pacman)

Endocytosis Pinocytosis: when the substance being engulfed is a LIQUID. Phagocytosis: when the substance being engulfed is a SOLID.

Vesicular Transport Exocytosis: When cells expel unwanted materials from vesicles.

Vesicular Transport http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf