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Transcript
CELL MEMBRANE DEFINITIONS Hydrophilic Having an affinity for water Hydrophobic Tending to repel water Amphipathic Molecules that contain both water soluble and water insoluble portions SURFACTANT DEMO WATER Formed by covalent bonds between 1 oxygen and 2 hydrogen atoms Unequal sharing of electrons Hydrogen have partially positive charge Oxygen has partially negative charge LIPIDS A diverse group of carbon compounds that are insoluble in water Examples: fat and oil PHOSPHOLIPID Contain hydrophilic phosphate group two hydrophobic hydrocarbon tails THOUGHT EXPERIMENT: PART 1 draw a beaker, and fill it 2/3 full of water imagine and draw how 5-10 phospholipid molecules would arrange themselves if they were dropped from above into this beaker of water THOUGHT EXPERIMENT: PART 1 Lipid Surface Monolayer THOUGHT EXPERIMENT: PART 2 Draw another beaker 2/3 full of water Draw more molecules such that they are submerged and surrounded by water. THOUGHT EXPERIMENT: PART 2 Lipid Micelle THOUGHT EXPERIMENT: PART 3 Draw another beaker 2/3 full of water Draw more molecules such that they are submerged and surrounded by water, but also able to contain water THOUGHT EXPERIMENT: PART 3 Phospholipid bilayer Cell Membrane In order to survive, cells must take in nutrients form the non-living environment outside of the cell and dispose of the wastes that build up inside the cell. These processes occur through the cell membrane. Regulating what enters and exits the cell is the main function of the cell membrane. Fluid Mosaic Model The current idea about the structure of the cell membrane is referred to as the Fluid Mosaic Model. The model was devised by Singer and Nicolson in 1972. Fluid Mosaic Model The cell membrane consists of two layers of phospholipids (a bilayer). Fluid Mosaic Model Cholesterol Component of animal cell membranes Molecule consists of a hydrophobic hydrocarbon with a hydrophilic hydroxyl group positioned between phospholipids Controls the fluidity and permeability of the membrane Fluid Mosaic Model Additionally, the cell membrane has a variety of proteins embedded in it. The embedded proteins have several functions. Types of Proteins Gatekeeper/ Channel proteins Provide paths through the membrane to allow specific molecules to pass freely. molecules move in and out more quickly than they could through regular diffusion and is known as facilitated diffusion. Types of Proteins Hormone receptors attach to hormones and pass the chemical message to the interior of the cell. Hormones have a special shape that fits into the protein receptor. Types of Proteins Identification proteins Display the identity of the cell Have a carbohydrate attached. Known as glycoproteins If a cell is not recognized as part of the organism, it may be attacked by the organism’s immune system. Types of Proteins Transport proteins Move specific molecules into or out of the cell against their concentration gradients (from low concentration to high concentration). This movement requires the use of energy and is known as active transport. Putting it all together Draw your version of the Fluid Mosaic Model Include: Phospholipids A range of proteins Cholesterol Label all parts