Membrane Structure and Function The plasma membrane controls what enters and leaves the cell.

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Lipid bilayer Lipid bilayer Hydrophilic heads Hydrophilic heads Hydrophobic tails Hydrophobic tails Proteins: Allow the passage of some molecules Proteins: Allow the passage of some molecules Carbohydrates: Cell recognition, Carbohydrates: Cell recognition, Occur on the outside cell surface only Occur on the outside cell surface only Cholesterol: makes membranes Cholesterol: makes membranes less fluid at warm temperatures (37 degrees) less fluid at warm temperatures (37 degrees) more fluid at cold temperatures more fluid at cold temperatures

Transcript of Membrane Structure and Function The plasma membrane controls what enters and leaves the cell.

Membrane Membrane Structure and Structure and

FunctionFunction

The plasma membrane The plasma membrane controls what enters and controls what enters and

leaves the cell.leaves the cell.

Plasma Membrane Plasma Membrane StructureStructure

Plasma Membrane Plasma Membrane StructureStructure

Lipid bilayerLipid bilayer Hydrophilic headsHydrophilic heads Hydrophobic tailsHydrophobic tails

Proteins: Allow the passage of some Proteins: Allow the passage of some moleculesmolecules

Carbohydrates: Cell recognition, Carbohydrates: Cell recognition, Occur on the outside cell surface onlyOccur on the outside cell surface only

Cholesterol: makes membranesCholesterol: makes membranes less fluid at warm temperatures (37 degrees)less fluid at warm temperatures (37 degrees) more fluid at cold temperaturesmore fluid at cold temperatures

Fluid Mosaic ModelFluid Mosaic Model Membranes must be fluid to work Membranes must be fluid to work

properly.properly.

The membrane is composed of The membrane is composed of many types of proteins embedded many types of proteins embedded in two layers of phospholipids. in two layers of phospholipids. Therefore a mosaic.Therefore a mosaic.

Traffic Across the Traffic Across the MembraneMembrane

Passive Transport vs. Active TransportPassive Transport vs. Active Transport

Passive Transport does not require Passive Transport does not require energy (ATP) from the cell.energy (ATP) from the cell.

Active Transport does require the Active Transport does require the input of cell energy (ATP).input of cell energy (ATP).

Passive TransportPassive Transport Diffusion- the Diffusion- the

net movement net movement of molecules of molecules from an area of from an area of high high concentration to concentration to an area of lower an area of lower concentration.concentration.

Passive TransportPassive Transport SolutionsSolutions Hypertonic: greater concentration of Hypertonic: greater concentration of

solutessolutes

Hypotonic: lower concentration of Hypotonic: lower concentration of solutessolutes

Isotonic: concentration of solutes is Isotonic: concentration of solutes is equalequal

Passive Transport: Passive Transport: OsmosisOsmosis

Osmosis- The Osmosis- The diffusion of diffusion of water across a water across a membrane.membrane.

Behavior of Cells in Behavior of Cells in Different SolutionsDifferent Solutions

Passive Transport: Passive Transport: Facilitated DiffusionFacilitated Diffusion

Facilitated Facilitated Diffusion: The Diffusion: The diffusion of diffusion of molecules with molecules with the help of a the help of a transport transport protein.protein.

Active TransportActive Transport Many cells must move Many cells must move

molecules against molecules against their concentration their concentration gradient (from areas gradient (from areas of low concentration of low concentration to higher to higher concentration).concentration).

This requires the This requires the input of cell energy input of cell energy (ATP).(ATP).

The Sodium Potassium The Sodium Potassium PumpPump

The Sodium Potassium The Sodium Potassium PumpPump

The Sodium Potassium The Sodium Potassium PumpPump

The Sodium Potassium The Sodium Potassium PumpPump

The Sodium Potassium The Sodium Potassium PumpPump

Bulk TransportBulk Transport Endocytosis- Bulk Endocytosis- Bulk

movement of movement of materials into the materials into the cell by means of a cell by means of a vesicle.vesicle.

Exocytosis- Bulk Exocytosis- Bulk movement of movement of materials out of the materials out of the cell by means of a cell by means of a vesicle.vesicle.