7.3 CELL TRANSPORT7.3 CELL TRANSPORT

CT Science Framework:CT Science Framework:

Explain the role of the cell Explain the role of the cell membrane in supporting cell membrane in supporting cell functions.functions.

A. Cell membraneA. Cell membrane

1.1. Functions:Functions:

a. protective a. protective barrierbarrier

b. gives b. gives structurestructure and and shapeshape

c. c. regulatesregulates what what entersenters and and exitsexits a cell a cell

A. Cell membrane ( cont.)A. Cell membrane ( cont.)

2. Structure of2. Structure ofa. a. DoubleDouble

membrane of membrane of lipidslipids

--likeslikes water ; water ; repels repels waterswaters

b. b. ProteinsProteins are are embedded within embedded within the layerthe layer

Photograph of cell Photograph of cell membranemembrane

The cell membrane is a The cell membrane is a fluid mosaicfluid mosaic of of lipidslipids, , proteinsproteins, , and and carbohydratescarbohydrates. .

FLUIDFLUID-- because the molecules because the molecules movemove about ; like a liquid about ; like a liquid MOSIACMOSIAC- because - because the proteins are scattered within the proteins are scattered within

the lipid layerthe lipid layer

B. Transport thru the cell B. Transport thru the cell membranemembrane

1. 1. DiffusionDiffusiona. passage of materials across a space a. passage of materials across a space from an area of from an area of high concentrationhigh concentration to to an area of an area of low concentrationlow concentration until an until an equilibriumequilibrium is reached is reachedb. b. ConcentrationConcentration:: thethe mass mass of a solute of a solute in a in a given given volumevolume of solvent of solvent (grams/liter)(grams/liter)

(example: 12 grams of salt in 3 liters of (example: 12 grams of salt in 3 liters of water-what is the concentration?)water-what is the concentration?)

Diffusion (cont)Diffusion (cont)

c. c. EquilibriumEquilibrium:: Concentration of a Concentration of a substance is the substance is the samesame across a across a spacespace

Diffusion (cont)Diffusion (cont)

Diffusion of a liquidDiffusion of a liquid

d. Factors that affect d. Factors that affect diffusiondiffusion

P E S T SP E S T S PermeabilityPermeability of the membrane of the membrane Electrical chargeElectrical charge of the substance- of the substance-

neutrally charged substances move neutrally charged substances move easiereasier

SizeSize of the molecule of the molecule TemperatureTemperature speeds up diffusionspeeds up diffusion SolubilitySolubility in water in water

A Cell’s EnvironmentA Cell’s Environmentisis

AQUEOUSAQUEOUS ( water-based) ( water-based)

Diffusion ( cont.)Diffusion ( cont.)

2. 2. OsmosisOsmosis is a type of:is a type of:

a. a. DiffusionDiffusion of water of water across a space across a space from a point of high concentration from a point of high concentration to a point of low concentrationto a point of low concentration

b. Depends upon the b. Depends upon the concentration concentration of a soluteof a solute in a given volume of in a given volume of solventsolvent which determines the type which determines the type of of cell solutioncell solution

Osmosis ( cont.)Osmosis ( cont.)3. CELL SOLUTIONS:3. CELL SOLUTIONS:

a. Isotonic Solutiona. Isotonic Solution: the amount : the amount of solute = the amount of of solute = the amount of solvent in and out of the cellsolvent in and out of the cell

Water moves in BOTH directionsWater moves in BOTH directions

IsotonicIsotonic

Isotonic solutionIsotonic solution

Osmosis Cont.Osmosis Cont.

b. b. Hypertonic SolutionHypertonic Solution: : Has a Has a high high concentration of solute vs. concentration of solute vs. solventsolvent

Cells Cells SHRINK because they lose SHRINK because they lose waterwater when placed in a when placed in a hypertonic solutionhypertonic solution

Example of hypertonic solution is Example of hypertonic solution is salt watersalt water

HypertonicHypertonic

Hypertonic SolutionHypertonic Solution

Osmosis ( cont.)Osmosis ( cont.)

c. Hypotonic solution: c. Hypotonic solution: Has a Has a LOW LOW concentration of solute vs. concentration of solute vs. solventsolvent

Cells Cells SWELLSWELL when placed in a when placed in a hypotonic solution because they hypotonic solution because they GAIN waterGAIN water

Example: Fresh waterExample: Fresh water

HypotonicHypotonic

Hypotonic SolutionHypotonic Solution

Solution Environments:Solution Environments:

Solution Environments:Solution Environments:

ISOTONIC

HYPERTONIC

HYPOTONIC

4. In other words……4. In other words……

a. a. In an isotonic solutionIn an isotonic solution…..…..

--____________________ happens to a cell, it looks happens to a cell, it looks the the ______________________

b. b. In a hypertonic solutionIn a hypertonic solution…….…….

-the cell -the cell __________________ due to due to water ________water ________

c. c. In a hypotonic solutionIn a hypotonic solution………….………….

-the cell -the cell ________________ due to due to water ________water ________

4. In other words……4. In other words……

a. a. In an isotonic solutionIn an isotonic solution…..…..

--nothingnothing happens to a cell, it looks the happens to a cell, it looks the samesame

b. b. In a hypertonic solutionIn a hypertonic solution…….…….

-the cell -the cell shrinksshrinks due to due to water losswater loss

c. c. In a hypotonic solutionIn a hypotonic solution………….………….

-the cell -the cell swellsswells due to due to water gainwater gain

5. Facilitated Diffusion5. Facilitated Diffusion

The use of membrane proteins to The use of membrane proteins to help diffuse large particles ( eg-help diffuse large particles ( eg-glucose, amino acids) across a cell glucose, amino acids) across a cell membrane.membrane.

Facilitated diffusionFacilitated diffusion

C. Passive TransportC. Passive Transport

1. Diffusion and osmosis are types of 1. Diffusion and osmosis are types of passive transportpassive transport..

a. Cell a. Cell does notdoes not use energy to move use energy to move a substance across the a substance across the membrane/space.membrane/space.

b. Cell energy is called b. Cell energy is called ATPATP

D. Active TransportD. Active Transport

1.1. Energy (ATP) is Energy (ATP) is requiredrequired to move a to move a substance across the membrane/space.substance across the membrane/space.

2.2. Involves moving large materials into Involves moving large materials into and out of cell.and out of cell.

3.3. Types ofTypes of--EndoEndocytosis: move materials cytosis: move materials intointo a cell a cell

- - ExoExocytosis: move materials cytosis: move materials out/exitsout/exits of cellof cell

EndocytosisEndocytosis