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MCAT Bio. Chem Ch. 8

QuestionAnswer
Fluid Mosaic Model Accounts for the presence of lipids, proteins, and carbohydrates in a dynamic, semisolid plasma membrane that surrounds cells.
The Plasma Membrane Contains Protein Embedded In: The phospholipid bilayer
Lipids In Plasma Membrane Move Freely In The Plane Of The Membrane And Can: Assemble into lipid rafts
Flippases Specific membrane proteins that maintain the bidirectional transport of lipids between the layers of the phospholipid bilayer in cells.
Proteins And Carbohydrates Are Slowed By: Their relatively large size
Plasma Membrane's Largest Component Lipids by mass and mole fraction
Triacylglycerols And Free Fatty Acids Act as phospholipid precursors and are found in low levels in the membrane
Glycerophospholipids Replace one fatty acid with a phosphate molecule, which is linked to other hydrophilic groups
Cholesterol Present in large amounts and contributes to membrane fluidity and stability
Waxes Present in very small amounts. Most prevalent in plants and function in waterproofing and defense.
Proteins In The Cell Membrane Act As: Transporters, cell adhesion molecules, and enzymes
Transmembrane Proteins Can have one or more hydrophobic domains and are most likely to function as receptors or channels.
Embedded Proteins Part of a catalytic complex or involved in cellular communication
Membrane-associated Proteins Act as recognition molecules or enzymes
Carbohydrates Can Form A Protective: Glycoprotein coat and also function in cell recognition.
Extracellular Lipids Can: Bind to membrane receptors, which function in channels or enzymes in second messenger pathways.
Cell-Cell Junctions Regulate: Transport intracellularly and intercellularly
Gap Junctions Allow for the rapid exchange of ions and other small molecules between adjacent cells.
Tight Junctions Prevent paracellular transport, but do not provide intercellular transport.
Desmosomes And Hemidesmosomes Anchor layers of epithelial tissue
Concentration Gradients Help determine appropriate membrane transport mechanisms in cells.
Osmotic Pressure (A Colligative Property) Pressure applied to a pure solvent to prevent osmosis and is used to express the concentration of the solution. AKA "Sucking" pressure in which a solution is drawing water in, prop. to its conc.
Passive Transport Does not require energy because the molecule is moving down its conc. gradient or from an area of higher conc. to an area with lower conc.
Simple Diffusion Does Not: Require a transporter. Small, nonpolar molecules move passively from an area of high conc. to an area of low conc. until equilibrium.
Osmosis Diffusion of water across a selectively permeable membrane
Facilitated Diffusion Uses transport proteins to move impermeable solutes across the cell membrane.
Active Transport Requires energy in the form of ATP or an existing favorable ion gradient. Can be primary or secondary depending on the energy source.
Symport / Antiport Further classification of secondary active transport
Endocytosis / Exocytosis Methods of engulfing material into or out of cells via the cell membrane
Pinocytosis Ingestion of liquid into the cell from vesicles formed from the cell membrane
Phagocytosis Ingestion of bacteria by phagocytes
Note About Specialized Membranes Some cells contain specialized membranes.
Membrane Potential Maintained by Sodium-Potassium pump and leak channels
Nernst Equation Calculates the electrical potential created by one ion
Goldman-Hodgkin-Katz Voltage Equation Derived from the Nernst Equation, this calculates the resting potential of a membrane at physiological temperatures.
Mitochondrial Membrane Differs From The Cell Membrane Because (Outer Mitochondrial Membrane Exp) Outer mitochrondrial membrane is highly permeable to metabolic molecules and small proteins.
Mitochondrial Membrane Differs From The Cell Membrane Because (Inner Mitochondrial Membrane Exp) Inner mitochondrial membrane surrounds the mitochondrial matrix, where the citric cycle produces electrons used in the electron transport chain, and where cellular respiratory enzymes are located. The inner membrane doesn't contain cholesterol.
Eq. 8.1: Osmotic Pressure II = iMRT. II = Osmotic pressure. M = molarity of the solution. R = ideal gas constant. T = absolute temperature (in Kelvins). i = van 't Hoff factor, aka the number of particles obtained from the molecule while in solution.
Eq. 8.2: Nernst Equation E = RT / zF * ln([ion outside] / [ion inside]) = 61.5/z * log ([ion outside] / [ion inside])
Eq. 8.3: Goldman-Hodgkin-Katz Voltage Equation Vm = 61.5 * log (PNa+ * [Na+] outside + PK+ * [K+] outside + PCl- * [Cl-] inside / PNa+ * [Na+] inside + PK+ * [K+] inside + PCl- * [Cl-] inside)
Created by: SamB91