Card Set Information
Membrane surrounding the cell
Everything that’s inside the cell
Fluid inside the cell.
Solid structures in the cell
Contains DNA instructions for the cell
Characteristics of plasma membrane
Composed of phospholipid bilayer.
*Selectively permeable allowing transfer of substances
Functions of plasma membrane:
*Barrier between internal and external environment of the cell.
*Movement of substance in and out of a cell
Arrangement of membrane proteins:
*Integral proteins- embedded. This includes the trans membrane protein.
*Peripheral proteins- located on the outside surface
Membrane proteins serve many functions:
Bind to ligand
Cell identity markers.
*Phospholipids are in constant motion.
*Plasma membrane and its components can move.
*Allows for movement of membrane during growth, maintenance, and repair
Some molecules can cross plasma membrane and others can’t.
*But Ion channels and transporters alter permeability.
*Permeable to small, uncharged nonpolar molecules. Examples are oxygen and carbon dioxide.
*Weakly permeable to small, uncharged polar molecules. Example is water.
Impermeable to ions and large molecules.
Gradients across the membrane
*Dependent on selective permeability.
*Electrical gradients (membrane potential).
*Mostly positive (+) outside and negative (-) inside a resting membrane potential.
Requires energy input from the cell
*A substance is driven against its concentration or electrical gradient.
*ECF has less solutes than ICF.
*H2O enters cell faster than it leaves
*Cell swells and may burst (lyse).
ECF has more solutes than ICF.
*Water leaves faster than it enters
*Cell shrinks (crenation).
Mechanism of passive transport (no energy