2 Cellular Transport Two ways to transport substances: How do substances move throughout the cell?Ever smelled cookies baking while you were in your bedroom?Two ways to transport substances:Without energy= Passive TransportWith energy = Active Transport
3 Diffusion is PassiveDiffusion (AKA Passive Transport)- net mvmt of particles from an area where there are many to an area where there are fewerAnimationThe amount of substances in a given area is called concentrationSubstances diffuse from high to low concentrationsTherefore, it doesn’t require energy!Fig. 7.20What if the concentrations are the same?When there is continuous movement of the particles, but no overall change in concentration it is called Dynamic Equilibrium
4 Three Main Factors of Diffusion Concentration- high concentration, fast diffusionTemperature- high temp, faster movementPressure- high pressure, particles are closer together and bounce into each other more often, faster diffusionCHEMISTRY!!!
5 Diffusion Across the Plasma Membrane Besides diffusing water across the cell, other ions and small molecules get diffused, tooFacilitated Diffusion- uses transport proteins to move other ions and small molecules across the plasma membrane
6 Types of Transport Proteins Used in Diffusion Channel proteins open and close the P.M. to allow the substance to diffuse that are polarCarrier Proteins change shape as they diffuse to help move substances through the membraneFig. 7.21Passive TransportReading Check- How do Na ions get into a cell?
7 Applications of Diffusion Kidney dialysisQuestion:Do substances need a stimulus to diffuse across a membrane?
8 Osmosis- Water’ You Doing? Diffusion of Water Water passes freely through the P.M. and doesn’t need transport proteinsThe diffusion of water is called osmosisRegulating water in the cell helps maintain homeostasisHow it works:Solute/solvent – which is which?Solute is the thing being dissolved, solvent does the dissolvingWater is the solventIf there is a lot of water, the concentration of the cell is low – it’s diluteFig. 7.22Reading Check- Compare and contrast osmosis and diffusion
9 Types of Solutions- Egg Demo Isotonic: Same concentration of water and solutes as its cytoplasm -Cells maintain normal shapeFig. 7.23Hypotonic: if cell is in a solution that has a lower concentration of soluteMore water outside of cell than inside, so the water flows in because of osmosis and the cell swellsToo much swelling can lead to a burst!Because plants of rigid cell walls, they don’t burst in hypotonic solutionsGrocers use this idea to keep veggies fresh by misting themThat’s how pickles are madeFig. 7.24
10 Hypertonic: the concentration of the solute outside of the cell is higher than inside Cells shrivel because the water is leaving the cell (less pressure)In plants, it causes wiltingFig. 7.25Evaluate the benefits of sports drinks that contain electrolytes that athletes drink instead of waterIs there any danger in consuming these drinks?Osmosis
11 Active TransportWhat if a substance has to move from an area of lower concentration to an area of higher?It requires energy and is called active transportOccurs in pumps- carrier proteins that help in transportCarrier ProteinsActive TransportFig Why does active transport require energy?
12 Na+/K+ ATPase Pump- A type of Carrier Protein Found in PM of animal cellsMaintains the level of sodium ions (Na+) and potassium ions (K+) inside and outside of the cellWhat is it used for?This protein pump is an enzyme to help with energy storing moleculesWhat’s it transport?Three Na+ out of the cell, 2 K+ into the cellWhy?The cell needs to get rid of Na+ and needs more K+But, since there’s lots of Na+ already on the outside of the cell and lots of K+ already on the inside of the cell, active transport has to be used
13 Na+/K+ ATPase PumpThree Na+ bind to the transport protein to move out of the cellThe transport protein requires ATP to change the shape of the proteinAfter the protein changes shape, it releases the Na+ to the outside of cellIn turn, the K+ on the outside of the cell bind to the proteinThe protein changes shape and releases the K+ on the inside of the cell
14 Transporting Large Particles Sometimes diffusion or transport proteins don’t get the job done because the particles are too largeEndocytosis is the process in which a cell surrounds the substance outside of the cell and engulfs it in the plasma membraneThe membrane then pinches off and leaves the substance inside the cellEndocytosisMovie
15 Transporting Large Particles Exocytosis is the opposite of endocytosisCells use it to expel wastes and secrete cell products, like hormones, that were manufactured inside the cellBoth Endo and Exo require energy to maintain homeostasis in the cellMovie
16 Visualize It! Look at figure 7.29 Make a Venn Diagram to compare and contrast the processes of endocytosis and exocytosis.
17 Questions to PonderIn what ways can materials move across a cell membrane?What is the difference between osmosis, diffusion and facilitated diffusion?Why are channel proteins needed?How do materials move against the concentration gradient?Pg Cutting Edge Biology