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31 Cards in this Set
- Front
- Back
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what is the function of the plasma membrane?
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boundary and selectively permeable
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phospholipids are amphipathic
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(both hydrophilic and and hydrophobic)
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Why are membranes organized into a bilayer>
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There are two “watery” areas that interact with the membrane, outside of the cell and inside the cell.
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How is this fluidity maintained?
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Kinks in unsaturated fatty acid tails of phospholipids
Cholestrol |
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How are proteins arranged to contribute to membrane function? (#1)
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Membrane proteins contribute to the mosaic quality of the structure.
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How are proteins arranged to contribute to membrane function? (#2)
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Different proteins convey different properties to each membrane.
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How are proteins arranged to contribute to membrane function? (#3)
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Integral proteins are inserted within the membrane.
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How are proteins arranged to contribute to membrane function? (#4)
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Peripheral proteins are attached to membrane surface
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How are proteins arranged to contribute to membrane function? (#5)
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Proteins attach to cytoskeleton or to extracellular fibers to help give animal cells a stronger framework.
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what is the function of the carbohydrates outside of the phospholipid bilayer?
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cell to cell recognition; Sorting cells into tissues; Immune defense; Usually oligosaccharides; glycolipids or glycoproteins
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how do ions and other polar molecules pass into and out of cells.
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transport proteins
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transport proteins...
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provide hydrophilic tunnel for ions and are specific for the substances they transport
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what determines the direction of traffic across a membrane
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diffusion
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what causes diffusion?
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concentration gradient represents potential energy.
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why is diffusion spontaneous?
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since the direction of movement decreases the free energy of the system it is spontaneous.
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does the diffusion of more than one kind of particle work together or separately?
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NO
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if a molecule can move freely through the phospholipid bilayer what always controls the directino of its movement?
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concentration gradient
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what is osmosis?
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diffusion of water across a semi-permeable membrane
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Which way will water move?
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water will follow the solutes!
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do water molecules stop moving in isotonic conditions
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no..they continue to diffuse, however there is no net movement.
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in general, which was does water move.
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hypotonic to hyertonic
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What is facilitated diffusion?
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diffusion of solutes with the help of transport proteins.
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why do solutes need a protein to facilitate their diffusion>
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they are too polar to pass thru the lipid bilayer
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what is active transport?
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pumps miloecules across the membrane against their concentration gradient and this requires energy in form of ATP.
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what is active transport used for
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to help maintain ionic gradients across membranes
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what do these ionic gradients represent?
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potential energy
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how is membrane potential maintained?
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an unequal distribution of anions inside the cell to cations outside the cell
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what two forces drive the diffusion of ions?
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concentration gradient and effect of membrane potential on the ion(electrochemical gradient)
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electrogenic pump
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a transport protein that generates coltage across a membrane
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endocyctosis-phagocytosis
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endocytosis of large particulate substances
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endocytosis-pinocytosis
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endocytosis of fluid and dissolved solutes
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