The Selectively Permeable Membrane Lab Problem What does selectively permeable mean?
The Cell (Plasma) Membrane Gateway to the Cell. Functions of Cell Membrane 1. Protective barrier 2....
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Transcript of The Cell (Plasma) Membrane Gateway to the Cell. Functions of Cell Membrane 1. Protective barrier 2....
The Cell (Plasma) The Cell (Plasma) Membrane Membrane
Gateway to the CellGateway to the Cell
Functions of Cell Functions of Cell MembraneMembrane1. Protective barrierProtective barrier
2.2. Regulates transport in & out of Regulates transport in & out of cell cell (selectively permeable)(selectively permeable)
3.3. Allows cell recognitionAllows cell recognition
4.4. Maintain ion concentrationMaintain ion concentration
Cell MembraneCell Membrane
The cell The cell membrane is membrane is flexibleflexible and and allows a allows a unicellularunicellular organism to organism to movemove
HomeostasisHomeostasis
•BalancedBalanced internal condition internal condition of cellsof cells
•Also calledAlso called equilibriumequilibrium
•Maintained by plasma Maintained by plasma membranemembrane controlling what controlling what enters & leaves the cellenters & leaves the cell
Structure of the Structure of the Cell MembraneCell Membrane
Polar heads are hydrophilichydrophilic “water loving”Nonpolar tails are hydrophobichydrophobic “water fearing”
Cell MembraneCell Membrane
Makes membrane “Selective” in what crosses
Phospholipid Bilayer
Fluid Mosaic Model(Lots of different types of molecules that assemble to form a function)
Cell MembraneCell Membrane
Hydrophobic molecules pass easily; hydrophillic DO NOT
The cell membrane is made of 2 layers of phospholipidphospholipids called the lipid bilayerbilayer
Small molecules and larger hydrophobic molecules move through easily.e.g. O2, CO2, H2O
Semipermeable Semipermeable MembraneMembrane
Ions, hydrophilic molecules larger than water, and large protein molecules do not move through the membrane on their own.
Semipermeable Semipermeable MembraneMembrane
SolutionsSolutions
• Solutions are made of solute Solutions are made of solute and a solventand a solvent
• SolventSolvent – The liquid part. It – The liquid part. It does the dissolving. does the dissolving.
• SoluteSolute – The thing being – The thing being dissolved. Salt and sugar are dissolved. Salt and sugar are solutes.solutes.
Types of Transport Types of Transport Across Cell Across Cell MembranesMembranes1. Diffusion2. Osmosis3. Facilitated
Diffusion4. Active Transport
DiffusionDiffusion
•Requires Requires NONO energyenergy
•Solutes move Solutes move from area of from area of HIGH to LOWHIGH to LOW concentratioconcentrationn
Diffusion: Draw this
Diffusion of LiquidsDiffusion of Liquids
Diffusion through a Diffusion through a MembraneMembrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
OsmosisOsmosis
• Diffusion of Diffusion of waterwater across a across a membranemembrane
• Moves from Moves from HIGH HIGH water potentialwater potential (low solute) to (low solute) to LOW water LOW water potentialpotential (high (high solute)solute)
Diffusion across a membrane
Semipermeable
membrane
Diffusion of HDiffusion of H22O Across O Across A MembraneA Membrane
High H2O potentialLow solute concentration
Low H2O potentialHigh solute concentration
Osmosis: Draw this
Types of SolutionsTypes of Solutions
• Hypotonic Hypotonic – concentration of – concentration of solute is higher INSIDE the cell.solute is higher INSIDE the cell.
• Hypertonic Hypertonic – concentration of – concentration of solute is higher OUTSIDE the solute is higher OUTSIDE the cell.cell.
• Isotonic Isotonic – concentrations of – concentrations of solutes is the same inside and solutes is the same inside and outside the celloutside the cell
Plant and Animal Cells put into various solutions
Facilitated Facilitated DiffusionDiffusion
Doesn’t require energy
Uses transport proteins to move high to low concentrationExamples: Examples: GlucoseGlucose or or amino acidsamino acids moving moving from blood into a from blood into a cell.cell.
Proteins Are Critical to Proteins Are Critical to Membrane FunctionMembrane Function
Facilitated DiffusionFacilitated Diffusion
Molecules will randomly move Molecules will randomly move through the through the porespores in in Channel Channel ProteinsProteins..
Facilitated DiffusionFacilitated Diffusion• SomeSome Carrier Carrier
proteinsproteins do not do not extend through the extend through the membrane.membrane.
• They They bond and bond and drag moleculesdrag molecules through the lipid through the lipid bilayer and release bilayer and release them on the them on the opposite side.opposite side.
Three Forms of Transport Across the MembraneThree Forms of Transport Across the Membrane
Active TransportActive Transport
Requires energy or ATP
Moves materials from LOW to HIGH concentration
AGAINST concentration gradient
Sodium-Potassium Sodium-Potassium PumpPump
3 Na+ pumped in for every 2 K+ pumped out; creates a membrane
potential
Think/Pair/ShareThink/Pair/Share
•Work with a partner Work with a partner to create different to create different situations that can situations that can be classified as be classified as diffusion.diffusion.
•Do the same for Do the same for osmosis.osmosis.