Cellular Transport

Cellular TransportCell Membranes and Interaction with their environmentCell MembranesStructure and FunctionsCell MembranesAll cells have a cell membraneFunctions: Controls what enters and exits the cell to maintain an internal balance called homeostasisProvides protection and support for the cell

Cell MembranesStructure of cell membraneLipid Bilayer -2 layers of phospholipidsPhosphate head is polar (water loving)Fatty acid tails non-polar (water fearing)Proteins embedded in membrane

ProteinsPolar heads love waterNon-polar tails hide from water.Cell MembranesCell membranes have pores (holes) in itSelectively permeable (semi-permeable): Allows some molecules in and keeps other molecules outTake cell membrane quiz!http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP1101

Cell TransportTypes of Cell TransportPassive Transport

Active TransportEndocytosis Exocytosis 7Passive TransportPassive TransportCharacteristicsTypes of Passive TransportNo energy required

Move due to gradientdifferences in concentration, pressure, charge

Move to equalize gradientHIGH low 1. Diffusion

2. Facilitated diffusion

3. Osmosis9VocabConcentration gradient is the different amounts of solutes or substances in one placeSolute a SUBSTANCE dissolved in a fluid

Solvent the FLUID part of a solution

Solution a MIXTURE of two or more substances (a solute and solvent)

DiffusionDiffusion is the movement of any particles from an area of HIGH concentration to an area of low concentration.

Molecules move to equalize concentrationEquilibriumEquilibrium occurs when the particles that were diffusing are now equally distributed

Movement Across the Cell MembraneA few molecules diffuse freely across the membrane:Water, Carbon dioxide, Ammonia, Oxygen

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Facilitated Diffusion2. Facilitated Diffusion is diffusion of specific particles through transport proteins found in the membrane Channels (are specific) help molecule or ions enter or leave the cellNo energy is used14

Process of Facilitated TransportProtein binds with moleculeShape of protein changesMolecule moves across membrane15

OsmosisOsmosis- diffusion of water through a selectively permeable membrane

Water is so small and there is so much of it the cell cant control its movement through the cell membrane.Equilibrium occurs until water is balanced on both sides of the membrane.

ONLY WATER DIFFUSES IN OSMOSIS!!!

Solute/Solvent/SolutionThis is sugar water.

What is the solute?What is the solvent?What is the whole mixture called?

Solute/Solvent/SolutionA glass of iced tea.

What is the solute?What is the solvent?What is the wholemixture called?

Solute/Solvent/SolutionEx: Propel Energy Drink

What is the solute?What is the solvent?What is the wholemixture called?

Solute/Solvent/SolutionEx: Dr. Pepper

What is the solute(s)?What is the solvent?What is the wholemixture called?

OsmosisWhat direction will the water go? are solutesTypes of Osmosis:Hypertonic solutions more dissolved solutesHypotonic solutions less dissolved solutesIsotonic solutions the same dissolved solutes

Hyper- means over, above, a lot

Hypo- means under, below

Iso- means equal or the same

Hypertonic Solution More solute outside the cellLess water outside the cell

Result: The WATER will move OUT of the cell, causing the cell to shrink (or crenate)

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions

Hypotonic SolutionLess solute outside of the cellMore water outside of the cell

Result: The WATER will move INTO the cell, causing the cell to swell or burst (lysis)

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions

Isotonic Solution Water is the same outside the cell and the same inside the cell.

Solutes are the same inside the cell as outside the cell.

Result: Water is moving in and out at the same rate

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions

How Organisms Deal with Osmotic PressureBacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure. A protist like paramecium have contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding.Salt water fish pump salt out of their specialized gills so they do not dehydrate.Animal cells are bathed in blood. Kidneys keep the blood isotonic by removing excess salt and water.

Paramecium (protist) removing excess water video

27Inquiry Osmosis Egg Lab A study of Tonicity in Cells Active Transport

Active TransportCharacteristicsTypes of Active TransportMolecular movement requires energy/ATP to move against the concentration gradientLOW high Example is sodium-potassium pump

EndocytosisExocytosis 30EndocytosisMovement of large materialParticlesOrganisms Large moleculesMovement is into cells Types of endocytosis bulk-phase (nonspecific) receptor-mediated (specific)

31Process of EndocytosisPlasma membrane surrounds materialEdges of membrane meetMembranes fuse to form vesicle

32Forms of EndocytosisPhagocytosis cell eatingPinocytosis cell drinking

33ExocytosisReverse of endocytosisCell moves material OUTSIDE the cell

34ExocytosisVesicle moves to cell surfaceMembrane of vesicle fuses Materials expelled

35Active Transportcell uses energy (in the form of ATP)actively moves molecules to where they are neededMovement from an area of low concentration to an area of high concentration (Low High)Three Types

Types of Active Transport1. Protein Pumps -transport proteins that require energy to do workExample: Sodium / Potassium Pumps are important in nerve responses.

Protein changes shape to move molecules: this requires energy!

Types of Active Transport2. Endocytosis: taking bulky material into a cell Uses energyCell membrane folds in around food particle creating a vesicle that is made of the cell membranecell eatingLysosomes come and digests foodThis is how white blood cells eat bacteria!

Types of Active Transport3. Exocytosis: Forces material out of cell in bulkmembrane surrounding the material fuses with cell membraneCell changes shape requires energyEX: Hormones or wastes released from cell