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15 Cards in this Set

  • Front
  • Back
Transport mechanisms exist so that
molecules can move across plasma
When they are able to move freely
molecules move from the area of
high concentration to an area of low concentration
molecules don’t move freely
across the plasma membrane
Glucose is an example.
Some molecules move easily across most cell membranes.
like water
two clusters of transport mechanisms
active transport. passive transport.
transport of molecules across a membrane requires energy
active transport.
does not require energy
passive transport.
Transport of molecules across a membrane follows the same principles as chemical reactions:
passive movement occurs from high energy to low energy; to move in the opposite direction requires the
input of energy
energy of a solution depends on the solute concentration
increases as solute concentration increases
A chemical driving force that acts on a given substance depends only
on the
concentration gradient of that particular substance.
Three types of driving forces influence the transport of molecules
electrical, electrochemical.
Any difference in energy existing across a membrane acts as
a driving force that tends to
push molecules in one direction of another.
a driving force that tends to
push molecules in one direction of another.
concentration differences or
other factors that affect the energies of the molecules.
molecules move from areas of high concentration to low
they move down their concentration gradient.
The rate of movement varies with the
size of the concentration gradient.