Biology 1107.docx - Biology 1107 Chapter 7 Plasma membrane...

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Biology 1107Chapter 7Plasma membrane: is the boundary that separates the living cell from its nonliving surroundings-It allows things in and out-It must be a phospholipid bilayer-Phospholipids in the plasma membrane can move within the bilayer-Fat doesn’t freeze and remains soft and flexible especially when it warms up-Can drift within the bilayer. It allows it to react faster in different areas.-The type of hydrocarbon tails in phospholipids: affects the fluidity of the plasma membrane.-The steroid cholesterol: has different effects on membrane fluidity at different temperatures. Phospholipids melts at different temps so we have different fats allows for temp variations.Six major functions of membrane proteins-Transport: allows some particles through-Enzymatic activity: speeds up reaction-Signal transduction: specific shape that fits the shape of a chemical messenger such as a hormone.-Cell-cell recognition: identification tags that are specifically recognized-Intercellular joining: how cells interlock, muscles and bones-Attachment to the cytoskeleton and extracellular matrix: anchoring points. Maintains cell shapeMembrane proteins and lipids-Are synthesized in the ER and Golgi apparatus-Membrane glycolipid are like the keys used to go in and outHydrophobic molecules-Are lipid soluble and can pass through the membrane rapidlyPolar molecules-Do not cross the membrane rapidlyDiffusion-Greater concentration to lower concentration movement until it reaches equilibrium

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