Movement through a Cell Membrane
Sec. 3-4 and 3-5
Cell Membrane
Outer lining or boundary of the cell.
Made up of phospholipid bilayers.
Have selective permeability which means it
allows some materials to cross the membrane.
Diffusion
Most cells are in a water solution, which means
water with particles dissolved into it.
Particles in solution move from areas of higher
concentration to lower concentration.
Osmosis
Osmosis is the diffusion of water molecules into
and out of the cell.
Passive Transport
Osmosis and diffusion is a form of passive
transport, meaning the cell exerts no energy to
do these.
Goes with the flow (concentration Gradient)
Facilitated Diffusion
A type of passive transport that uses
helpers/membrane proteins to move substances.
Still require no energy.
Active Transport: Movement of molecules from
an area of low concentration to higher
concentration. This requires transport
(membrane) proteins and use of chemical
energy.
Goes against concentration Gradient
With your table group:
Compare and Contrast Passive and Active
Transport
Section 3.4 in textbook
Cell Solutions: Isotonic
Most cells are in a water solution, which means
water with particles dissolved into it.
Isotonic solution is when the concentration of
dissolved substances (outside the cell) is the
same as the concentration inside the cell.
Results in no net movement of water
(equilibrium).
Hypotonic
Hypotonic solution is when the concentration of
dissolved substances (outside the cell) is lower
than the concentration inside the cell.
Will result in movement of water into the cell.
The cell will swell
Turgor pressure causes the swelling in animal
cells but supports plant cells due to cell wall.
Hypertonic
Hypertonic solution is when the concentration of
dissolved substances is Higher than the
concentration inside the cell.
Will result in movement of water out of the cell.
The cell will shrivel or shrink
Endocytosis and Exocytosis
Endocytosis is the process of taking liquids or
fairly large molecules into the cell by engulfing
them in the membrane. Phagocytosis is the
engulfing of large particles
Exocytosis is the process of releasing liquids or
fairly large molecules from the cell by engulfing
them in the membrane.