Biology 1033 Exam 2 Dr. Hasek
Questions & Answers
transmembrane proteins - ANSWERSTransmembrane proteins are integral proteins
that do not extend all the way through the membrane.
fluidity of membranes - ANSWERSPhospholipids in the plasma membrane can move
within the bilayer
Most of the lipids, and some proteins, drift laterally
Rarely does a molecule flip-flop transversely across the membrane
selectively permeable membrane - ANSWERSmembrane that allows some substances
to pass more easily than others and blocks the passage of some substances altogether
passive transport - ANSWERSRequires NO energy, Movement of molecules from high
to low concentration, Moves with the concentration gradient
active transport - ANSWERSEnergy-requiring process that moves material across a cell
membrane against a concentration difference
transmembrane gradient - ANSWERSconcentration of a solute is higher on one side of
a membrane than the other
electrochemical gradient - ANSWERSThe diffusion gradient of an ion, representing a
type of potential energy that accounts for both the concentration difference of the ion
across a membrane and its tendency to move relative to the membrane potential.
isotonic - ANSWERSwhen the concentration of two solutions is the same
Hypotonic - ANSWERSHaving a lower concentration of solute than another solution
Hypertonic - ANSWERSHaving a higher concentration of solute than another solution.
transporters - ANSWERSmechanisms in the membrane of a cell that actively transport
ions or molecules across the membrane
Uniporter - ANSWERSA carrier protein that transports a single molecule across the
plasma membrane.
sodium-potassium pump - ANSWERSa carrier protein that uses ATP to actively
transport sodium ions out of a cell and potassium ions into the cell
Exocytosis - ANSWERSProcess by which a cell releases large amounts of material
