Cellular Transport
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Transport Factors (Types)
1. Passive Transport
a) Diffusion
b) Osmosis
2. Active Transport
a) Carrier Proteins
b) Endocytosis
1) Pinocytosis
2) Phagocytosis
c) Exocytosis
1) Secretory Vesicles
2) Excretory Vacuoles
Diffusion<---> Osmosis
 Diffusion is the tendency of objects in high
concentration (state of order) to flow to an
area of low concentration (state of disorder).
 Facilitative Transport --> transport proteins
 Osmosis is diffusion through a
semipermeable membrane.
 Hypotonic--H2O low inside
 Hypertonic-- H2O high inside
 Isotonic-- H2O equal on inside/outside
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Active Transport
 Ion assisted transport Molecules or ions help
the substance getting transported to get
across the membrane.
 Receptor Site (gate) assisted transport The
shape and attractions of the receptor (gate)
help the substance getting transported to get
across the membrane.
 Energy assisted transport Energy to help
transport substances is received from ATP,
helping the substance getting transported to
get across the membrane.
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Semipermeable Membrane
 Smaller molecules are
free to pass through the
membrane equally in
both directions <-->.
Diffusion Rules!
 Larger molecules are
not free (or are greatly
slowed down) to pass
through the membrane
in either direction.
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Transport Protein (facilitative)
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 Sodium (Na) and
Potassium (K) are at
equilibrium (diffusion).
This nerve cell would be
inactive.
 The receptor site
(sodium pump) collects
sodium (Na) ions. ATP
activated the “sodium”
pump.
 Sodium gets transported
against the diffusion
gradient and potassium
(K) load onto the carrier
molecule and go inside
the cell
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ATP energy assist
Hypertonic Solution
 The solutes on the outside
of the cell are in higher
concentrations, water is in
low concentration.
 The concentration of water
is higher inside the cell.
 The result is that water
flows ________ the cell.
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Isotonic Solutions
 The concentration of
solute is equal on both
sides of the cell.
 The concentration of
water is equal on both
sides of the cell.
 The flow of water is
______.
Hypotonic Solutions
 Concentrations of
solutes are greater
inside the cell, water
concentration is lower
 Concentrations of
water are higher
outside the cell.
 The result is that water
flows _______ the cell.
 Molecules come in
contact with the cell’s
bilipid layer.
 The bilipid layer
responds by folding in.
 The substance is
completely surrounded
by the cell membrane,
which goes into the cell.
 The cell membrane
breaks up and the
molecules are now
inside the cell.
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Pinocytosis
 Similar to pinocytosis
but often involves
larger molecules.
 Note that cell
membrane becomes a
food vacuole that
remains intact.
 After digestion the food
vacuole becomes a
excretory vesicle.
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Phagocytosis