Bio Mid Term 1 Study Notes.docx

Membrane causing the water inside the cell to rush

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membrane, causing the water inside the cell to rush outwards, shrinking the cell size Isotonic: solution where the solute concentration is equal inside and outside the cell Exocytosis: when a vesicle breaks off from the cell membrane, releasing its contents outside the cell; the proteins that are part of the vesicle membrane become part of the plasma membrane Endocytosis: membrane forms a pocket over solute outside the cell. The membrane then is pinched off as a vesicle.
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Eukaryotic membranes follow the fluid mosaic model. It composes of a phospholipid bilayer than has cholesterol, integral proteins, and peripheral proteins. Membranes are fluid. Eukaryotic membranes provide structure and support while also allowing molecules/ions to enter and exit the cell o Allow nutrients to enter cell while excreting waste The fluid mosaic model suggests that the membrane is fluid and that there are multiple “pieces” (proteins, carbs, phosopholipid bilayer, glycolipid) Factors affecting fluidity: o Temperature: as the temperature goes up, cell fluidity increases, and saturated fats also increase to minimize changes in fluidity. If gone up too high, leakage of ions can occur, upsetting the balance of ions in the membrane, leading to cell death. If the temp goes done too much, the cell becomes too rigid and as a result is less permeable and inhibit functions of enzymes and receptors attached to the membrane. o Saturation: presence of double bonds in the fatty acid chains of phosophlipid bilayer will cause the cell to be more fluid as the double bond causes a bend in the tail which allows the phosopholipids to pack loosely amongst one another. Temperature goes up = increase of saturated fats Temp goes down = increase of unsaturated fats The plasma membrane has selective permeability by having certain passageways that only certain molecules can fit through. In order for other molecules that cant fit through to pass through the membrane, proteins must be used. Phospholipid bilayers’ fatty acid chains provide fluidity/rigidity for the cell o Proteins allow the transport of large molecules Passive transport: movement of a solute across a membrane along the concentration gradient; does not require energy o Passive diffusion: movement of solute from area of high to low concentration without the use of transport proteins o Facilitated Diffusion: movement of solute from area of high to low concentration with the use of a carrier protein Uniport: when carrier protein binds to one solute at a time Active Transport: movement of a solute across a membrane against the concentration gradeitn; requires energy o Primary active transport: direct use of the energy obtained from hydrolysis of ATP in order to allow transport proteins to directly carry solute across the membrane against the concentration gradient o Secondary Active Transport: the concentration gradient of the ions moved with the hydrolysis of ATP from primary transport is used to
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