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31 Cards in this Set

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