Download Passive Transport Notes

Cell Membrane Transport
PASSIVE TRANSPORT

Moves molecules from an area of high concentration to low concentration
Down the concentration gradient

Does Not Require Energy!

Diffusion
Osmosis
Movement of molecules across a
semipermeable membrane
Diffusion of water molecules across
a semipermeable membrane



A solution with the same concentration of solutes as the
cell
Size stays constant as water
enters and exits the cell
Example:
Solution: 5% NaCl, 95% Water
Hypertonic Solution

A solution with more
solutes than the cell
 More water exits causing the
cell to shrink or
possibly die
 Example:
Solution: 5% NaCl, 95% Water

Diffusion through transport
proteins
Outside
(high)
Three Types of Solutions
Isotonic Solution
Facilitated Transport
Inside
(low)
Hypotonic Solution

A solution with less
solutes than the cell
 More water enters the cell
causing the cell to expand or
possibly burst
 Example:
Solution: 3% NaCl, 97% Water
Cell:
2% NaCl,
98% Water
Cell: 5% NaCl, 95% Water
Vocabulary:
Solution - homogeneous mixture of two or more substances
Solvent - the substance doing the Dissolving (ex. Water in salt water)
Solute - the substance which is dissolved (ex. Salt in salt water
Cell:
5% NaCl,
95% Water
Transport
Protein