CELLULAR
TRANSPORT
CELL MEMBRANE
 All
cells have cell membranes
 The functions of the cell membrane are
→Controls
what enters and exits the
cell to maintain an internal balance
called homeostasis
→Provides protection and support for
the cell
STRUCTURE OF CELL MEMBRANE
Lipid
bilayer = 2 layers of phospholipids
Phospholipids have a hydrophilic head
and a hydrophobic tail
Hydrophilic = water loving
Hydrophobic = water fearing
Cell Membrane
CELL MEMBRANE & TRANSPORT
Cell
membranes are selectively
permeable: it allows some molecules in
and keeps other molecules out
The structure of the cell membrane
helps it be selective
Molecules in motion have kinetic energy
TYPES OF CELLULAR TRANSPORT
PASSIVE TRANSPORT
Cell does not use energy
ACTIVE TRANSPORT
Cell has to use energy
DIFFUSION
PROTEIN PUMPS
FACILITATED DIFFUSION
ENDOCYTOSIS
OSMOSIS
EXOCYTOSIS
PASSIVE TRANSPORT
 Cell
uses NO energy
 Molecules move randomly
 Molecules go from an area of HIGH
concentration to LOW concentration
 3 types : diffusion, facilitated diffusion,
osmosis
1. DIFFUSION
Diffusion:
random movement of
particles from an area of high conc. to an
area of low conc.
Diffusion continues until all molecules
are evenly spaced (equilibrium is
reached)
Molecules will still move around but stay
spread out
Animation
1. DIFFUSION
2. FACILITATED DIFFUSION
Diffusion
of specific particles through
transport proteins found in the
membrane
Transport Proteins are specific – they
“select” only certain molecules to cross
the membrane
Also goes down a concentration
gradient (HIGH → LOW)
Animation
2. FACILITATED DIFFUSION
3. OSMOSIS
Diffusion
of water through a
selectively permeable membrane
Many molecules dissolve in water
Molecule is the solute
Water is a solvent
Osmosis is diffusion of water from high
concentration to low concentration
Animation
3. OSMOSIS
SALT SUCKS!
TYPES OF SOLUTIONS
 HYPERTONIC
SOLUTION
 ISOTONIC SOLUTION
 HYPOTONIC SOLUTION
1. HYPERTONIC
 The
solution has a higher
concentration of solutes
and a lower concentration
of water than inside the
cell.
 OUTSIDE CELL: High
solute/Low water
 Water goes from inside
the cell to outside
 Cell SHRINKS
2. ISOTONIC
 The
solution has an equal
concentration inside and
outside the cell.
 Water moves equally in
both directions
 Cell stays the same size
3. HYPOTONIC
 The
solution has a lower
concentration of solutes and
a higher concentration of
water than inside the cell.
 OUTSIDE CELL: Low
solute/High water
 Water goes from solution
into the cell
 Cell SWELLS & BURSTS
TYPES OF SOLUTIONS
ACTIVE TRANSPORT
 Cell
has to use energy
 Happens AGAINST a concentration gradient
 Molecules go from LOW concentration to
HIGH concentration
 Difference between active and passive
transport is the direction of movement
1. PROTEIN PUMPS
Transport
proteins that require energy
(ATP) move the molecules in and out
Example: Sodium/Potassium Pumps
1. PROTEIN PUMPS
2. ENDOCYTOSIS
Transporting
Uses
bulky material into a cell
energy
Cell membrane in-folds
around food particle
“Cell Eating”
Forms food vacuole & digests food
This is how white blood cells eat bacteria!
2. ENDOCYTOSIS
PHAGOCYTOSIS
PINOCYTOSIS
ACTIVE VS PASSIVE TRANSPORT