The Plasma Membrane Gateway to the Cell copyright

The Plasma Membrane - Gateway to the Cell copyright cmassengale 1

Photograph of a Cell Membrane copyright cmassengale 2

Homeostasis • Balanced internal condition of cells • Also called equilibrium • Maintained by plasma membrane controlling what enters & leaves the cell copyright cmassengale 3

Functions of Plasma Membrane ü Protective barrier ü Regulate transport in & out of cell permeable) (selectively ü Allow cell recognition ü Provide anchoring sites for filaments cytoskeleton of üContains the cytoplasm (fluid in cell) copyright cmassengale 4

Membrane Components Phospholipids Cholesterol Proteins (peripheral and integral) copyright cmassengale 5 Carbohydrates (glucose)

Cell Membrane Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “Selective” copyright cmassengale in what crosses 6

Solubility • Materials that are soluble in lipids can pass through the cell membrane easily copyright cmassengale 7

Semipermeable Membrane Small molecules and larger hydrophobic molecules move through easily. e. g. O 2, CO 2, H 2 O copyright cmassengale 8

Semipermeable Membrane Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. copyright cmassengale 9

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