2 Warm-UpWhat do you know so far about the cell membrane? What do you want to know about the cell membrane?
3 Cell Membrane Structure & Function Phospholipid Bi-layer (hydrophilic heads, hydrophobic tails)Fluid-Mosaic ModelProteins & cholesterol embedded within the phospholipid bi-layerSelectively Permeable – controls was enters and exits the cell
4 Fluid-Mosaic Model Channel Proteins: Allow molecules, such as water, to pass through the cell membraneRecognition/ID Protein:Has carbohydrate chains attached that are used as ID markersAllow cells to communicate with eachother and identify foreign invaders (other blood type, virus)
5 Fluid-Mosaic Model Protein Pump: Cholesterol: Use ATP (energy) to pump substance across the membraneCholesterol:Lipid that controls the fluidity of the cell membrane
6 Cell membrane transport There are 2 types of cell membrane transport:Passive TransportThings flow fromHigh to lowActive TransportLow to high
7 Another perspective on passive and active transport
8 Passive Transport Diffusion The movement of particles from areas of high concentration to low concentration
9 EquilibriumWhen is equilibrium reached when discussing cell membrane transport?When the concentrations of particles are the same on both sides
10 Facilitated Diffusion Particles flow from high concentration to low concentration but this time they need the help of proteins to get through the cell membrane.
12 Passive transport Osmosis The diffusion of water across a selectively permeable membraneImportant in maintaining cell homeostasisWater flows to side of membrane where the water concentration is lower until equilibrium is reached
13 OsmosisOsmosis is controlled by the amount of solutes on either side of a membrane
14 Osmosis – Types of Solutions When dealing with osmosis, water can either move into the cell or out of it.The solute can not move to equal out the solution so the water has to.We describe the solutions that cells are in as either hypotonic, isotonic, or hypertonic.90%What are the concentrations?40%
15 Isotonic SolutionIsotonic solution – Concentration of solute is the same in the cell and the area around the cell.Give me an example of an isotonic solution that some of you use everyday
17 Hypotonic SolutionHypotonic Solution – Concentration of solute is lower in the solution than in the cell.Where is water going to move in order to reach equilibrium (Equal concentrations)?Inside the cell
18 Hypotonic solutionsSince water moves into the cell the cell can explodeSo, Hypotonic solution, low concentration of solute, cell can explode
20 Hypertonic SolutionHypertonic solution – concentration of solute is higher in the solution than in the cell.Where is water going to move in order to reach equilibrium (Equal concentrations)?Outside the cell
21 Hypertonic solutionsSince water moves out of the cell the cell will shrinkSo, Hypertonic solution, high concentration of solute, cell will shrink
22 Plant and animals cells in a Hypertonic Solution
24 Active TransportMolecules move from low concentration to high concentrationRequires energy….why?
25 Active Transport Molecular Transport – Bulk Transport Protein Pumps Small molecules and ions carried across the cell membrane by proteins in the membrane that act like pumpsBulk TransportEndocytosis – in!Exocytosis – out!
26 Other membrane transport activities that require energy EndocytosisEngulfing of large particles or liquids from outside the cell
27 2 types of Endocytosis Phagocytosis Pinocytosis Engulfing of large particlesfrom outside the cellPinocytosisEngulfing ofliquids fromoutside the cell
28 Other membrane transport activities that require energy ExocytosisRelease of large particles or liquids from inside the cellOutside the cellInside the cell