Osmosis, Diffusion And Cell Transport
Osmosis, Diffusionand Cell Transport
Types of TransportThere are 3 types of transport in cells:1. Passive Transport: does not use thecell’s energy in bringing materials in & outof the cell2. Active Transport: does use the cell’senergy in bringing materials in & out of thecell3. Bulk Transport: involves the cellmaking membrane bound vesicles to bringmaterials in & out of the cell
Passive TransportThere are 3 types of passive transport:1. Diffusion: involves small or unchargedmolecules entering & leaving the cell2. Osmosis: involves water entering &leaving the cell3. Facilitated Diffusion: involves large orcharged molecules that need a proteinhelper to get in & out of the cell
DiffusionDiffusion is the net movement of asubstance (liquid or gas) from an area ofhigher concentration to one of lowerconcentration. A drop of dye in water isconcentrated but then begins to dispersethrough out the water moving froman area of highto an area of lowconcentration.
DiffusionWhen the substance has fully dispersed throughout the container, it has reached equilibrium.Notice in the picture below how molecules A andB are evenly distributed through out thecontainer. When equilibrium has beenreached, there is no longer aconcentration gradient. Aconcentration gradient is thedifference in concentrationbetween two areas.
DiffusionCertain molecules can freely diffuse acrossthe cell membrane. Look at the picturebelow- hydrophobic molecules and smalluncharged molecules candiffuse through themembrane but largemolecules or ions(atoms with a positiveor negative charge)can not movethrough themembrane.
OsmosisOsmosis is the diffusion of water from an area of highconcentration to an area of low concentration across amembrane. Cell membranes are completely permeableto water and the amount of water in the environment hasa large effect on the survival of a cell. The picture showsa tube separated bya membrane and howthe water moves froman area of highconcentration to anarea of low.Little soluteLots of soluteLots of waterLittle water
OsmosisThere are 3 types ofsolutions that involvewater and how theyaffect the cell. They are:1. Hypertonic Solution: thesolution the cell is placed inhas less water than the cell2. Hypotonic Solution: thesolution the cell is placed inhas more water then the cell3. Isotonic Solution: thesolution the cell is placed inhas equal amount of water asthe cell
Hypertonic SolutionIn a hypertonic solution, there is a higher concentration of waterinside the cell than outside the cell. A hypertonic solutionhas more solute (salt, sugar, etc.) than the cell and thiscauses there to be less water in the solution. Water flows from an area ofhigh concentration to an area of low and leaves the cell. This loss of watercauses the cell to shrivel.In animal cells, the shriveling is called crenating. The red blood cells in thepicture to the left have crenated. In plant cells, plasmolysis occurs and thecell membrane shrinks away from the cell wall. Death will result in bothcells.Plasmolysis occurring in a plant cellCrenated red blood cellsNormal cellCell inplasmolysis
Hypotonic SolutionIn a hypotonic solution, the solution contains a higherpercentage of water than the cell. A hypotonicsolution has less solute than the cell and this causesthe solution to have more water than the cell. When a cell is placedin a hypotonic solution, water flows from an area of highconcentration to an area of low and rushes into the cell. Thiscauses the cell to expand and possibly burst.In animal cells, the cell bursts or will lyse, killing the cell. In plant cells,the cell membrane is pressed up against the cell wall but the cellwall does not allow the cell to expand anymore and the plant celldoes not die.Plant cell in aHypotonic solutionRed blood cells beginning to lyse
Isotonic SolutionIn an isotonic solution, there is the samepercentage of water on the outside of thecell as the inside of the cell. An isotonicsolution has the same amount of solute asthe inside of the cell. Water moves at aconstant rate in and out of the cell and thecell maintains its original shape.In animal and plant cells, the cell keeps itsshape when in an isotonic solution. Mostcells live in an isotonic environment andthey are able to maintain their shape andsurvive.Plant cells in anisotonic solutionRed blood cell in an isotonic solution
Hypertonic and Hypotonic SolutionsThe plant cell to the left is placed indistilled water and salt solution.Notice what happens to the cell in thedifferent types of solutions.The red blood cell to the right is placed indistilled water and salt solution.Notice what happens to the cell in thedifferent types of solutions.
Facilitated DiffusionSome molecules are too large to pass through the cell membrane by diffusionand need help to cross. These molecules use facilitated diffusion.Facilitated diffusion is the flow of large molecules from an area of highconcentration to an area of low using proteins in the cell membrane.Glucose is able to enter our cellsfrom the blood stream byfacilitated diffusion. A glucosemolecule is too big to squeezethrough the phospholipidbilayer and needs proteinchannels to help it pass intothe cell. These protein“helpers” are extremely importantbecause they allow much neededmolecules to enter our cells. Without them, our cells would not haveglucose and our cells would not beable to make energy.
ActiveTransportThe types of transportdiscussed so far arepassive transport and doNOT require a cell to useits energy- the moleculesflow with the concentrationgradient. There are timeswhen the cell wants topump against the gradientand to do so, it must useenergy. The use of energyto pump molecules againstthe gradient is calledactive transport. A celluses energy in the form ofATP (adenosine triphosphate). When energyis taken from ATP, it turnsinto ADP.The sodium-potassium pump in nerve cells is anexample of active transport. Sodium and potassiumatoms are pumped against the gradient using ATP.By pumping against the gradient, the cell builds aneven bigger gradient (difference betweenconcentrations across the membrane) that helpsnerve impulses.
Bulk TransportThe last kind of cell transport is bulk transport. Bulk transport involvesthe cell membrane making vesicles to bring materials in and out ofthe cell. There are two kinds of bulk transport:1. Exocytosis: movingmaterials OUT of the cell.2. Endocytosis: movingmaterials INTO the cell.There are 2 types ofendocytosis:1. Pinocytosis: bringingsmall molecules or liquidsinto the cell2. Phagocytosis: bringinglarge molecules into the cell
ExocytosisExocytosis is the process of exporting materials out of the cell byforming a membrane bound vesicle around the materials. The celluses exocytosis to get rid of cell waste or to export proteins made inthe cell to give to other cells.The proteins or waste are taken to the golgi body where the materialsare packaged into a membrane bound vesicle. The vesicle thenmerges with the cell membrane and the materials are released intothe outside environment.Micrograph of a vesicleexpelling its contentsexocytosis
Endocytosis-PinocytosisEndocytosis is the movement of materials into the cell throughmembrane bound vesicles. One type of endocytosis is calledpinocytosis, or “cell drinking”. Pinocytosis is the movement of smallmolecules or liquids into the cell through bulk transport.The small molecules make contact with the cell membrane and the cellmembrane pinches off around the molecules. Pinocytosis is howanimal cells make vacuoles (water filled sacs).Pinocytosis occurring intwo separate cells
Endocytosis-PhagocytosisThe other type of endocytosis is phagocytosis, or “cell eating”.Phagocytosis is the movement of largemolecules into the cell through bulk transport.The large molecules make contact with the cellmembrane and the cell membrane pinches offaround the molecules. The lysosomes thenfuse with the vesicle and break down the largemolecules into nutrients. Phagocytosis is howwhite blood cells engulf bacteria and breakthem down.Micrograph of a white blood cellengulfing virus particles.A cell taking in a food particleand breaking it down.
EndocytosisABAbove are examples of endocytosis. Determine what type ofendocytosis is shown in each situation. Notice the micrograph ofactual cells performing the different types of endocytosis.
Types of Transport There are 3 types of transport in cells: 1. Passive Transport: does not use the cell’s energy in bringing materials in & out of the cell 2. Active Transport: does use the cell’s energy in bringing materials in & out of the cell 3. Bulk Transport: involves the cell making me
Diffusion, Osmosis, and Osmoregulation NOTES January 23, 2012 Passive vs. Active Transport Passive Transport - the movement of molecules, into or out of cells, with the concentration gradient. * No energy required by the cell. * Examples: diffusion and osmosis *Active Transport - the movement of molecules, into or out of cells, against the .
energy –referring to active transport, exocytosis and endocytosis. The correct processes that the molecules Louise was may utiliseinclude A. osmosis, simple diffusion and active transport. B. osmosis and simple diffusion. C. osmosis and exocytosis. D. simple diffusion, exocytosis and endocytosis
Diffusion Osmosis is the diffusion of water through a selectively permeable membrane. - water moves down concentration gradient - passive . Lesson Overview Cell Transport Osmosis: An Example of Facilitated Diffusion Hypertonic - higher concentration of solute; low concentration of solvent
AP BIOLOGY NAME_ CELL UNIT ACTIVITY #6 DATE_HOUR_ DIFFUSION AND OSMOSIS LAB INTRODUCTION: In this laboratory you will investigate the processes of diffusion and osmosis in a model membrane system. You will also investigate the effect of solute concentration on w
Lab 4: Diffusion and Osmosis (Revised Fall 2009) Lab 4 - Biol 211 - Page 1 of 23 Lab 4. Diffusion and Osmosis in Selectively Permeable Membranes Prelab Assignment Before coming to lab, read carefully the introduction and the procedures for each part of the experiment, and then answer the prelab q
Section 7-3 Diffusion, Osmosis, Facilitated Diffusion, and Active Transport PASSIVE TRANSPORT: no energy required Diffusion: the process by which substances move from higher concentration to areas of lower concentration. Continues until equilibrium is reached. Osmosis: diffusio
A active transport B bulk flow C osmosis D facilitated diffusion Movement of water out of a cell resulting in the collapse of the plasma membrane surrounding the central vacuole. 4 A bulk flow B osmosis C facilitated diffusion D plasmolysis 5 Movement of solutes across a plasma membrane requiring addition
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