Membranes - Functions of Membranes 1. Regulate the movement...

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Functions of Membranes 1. Regulate the movement of substances into and out of cells and organelles 2. Allow maintenance of stable internal environment 3. Separate space into specialized regions by functions not compatible with one another Parts of Membranes 4. Phospholipid bilayer o The fundamental structure of the membrane o Phospholipids Have hydrophobic and hydrophilic parts Makes a "hollow" membrane o Evidence Freeze-fracture the membrane and observe protein bumps Essentially peel the phospholipid layers apart 5. Fluid-Mosaic Model of a membrane o Membranes are typically "fluid" with the consistency of salad oil; although membrane fluidity depends on temperature. o Membranes are a mosaic of phospholipids and proteins. o Evidence Took cell from a mouse and a human Marked the different proteins on the cells with chemical dyes Fused the cells to create a hybrid cell After an hour, the different proteins from both cells mixed within the membrane o Effect of unsaturated and saturated phospholipids on membrane fluidity Unsaturated Hydrocarbon tails of lipids have kinks Makes the membrane more fluid Saturated Lipid tails are straighter Makes the membrane more viscous Cholesterol in Animal Membranes 6. Cholesterol macromolecules are stuck in the lipid tails within the membrane
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Membranes - Functions of Membranes 1. Regulate the movement...

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