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Cellular Transport
Involves the absorption and
circulation of materials
Plasma Membrane
controls the movement of molecules into
or out of the cell
 Selectivity Permeable
( Based on SIZE of Molecules )
Monomers- Small
Polymers - Big

Plasma Membrane
– materials ENTER the cell
 circulation – materials are moved
throughout the cell
 cyclosis – the circulation of the
cytoplasm
cyclosis animation
 absorption
Fluid Mosaic Model of Plasma
Membrane

flexible structure made up primarily of
lipids and proteins
Membrane movement animation
Proteins

proteins are embedded in the bilayer:

transport proteins help some substances
move in or out
Types of Cellular Transport
I. Passive Transport
Weeee!!
!
no energy required
no cellular energy required
A. Diffusion
B. Osmosis
C. Facilitated Diffusion
high
low
A. Simple Diffusion
Passive Transport
A. Simple Diffusion
Simple Diffusion
 substance passes
through a
membrane without
the aid of transport
proteins
Simple Diffusion

there is a net
movement of
molecules from
areas of high
concentration to
areas of low
concentration
Concentration Gradient

molecules move
with the
concentration
gradient
Molecules that are able to diffuse:
Oxygen
Carbon dioxide
Water
Simple Diffusion

diffusion stops once molecules are
evenly distributed = dynamic
equilibrium

molecules are still in constant motion,
but same number of molecules move in
one direction as in the opposite
direction
B. Osmosis
 diffusion
of water
through a selectively
permeable membrane
 water moves from a
high to a low
concentration
1. Hypotonic Solutions
have a lower concentration of solutes
(dissolved substances) and a higher
concentration of water than inside the
cell
Hypotonic Solutions
Result: water
moves from the
solution to inside
the cell: cell
swells and
bursts open
(cytolysis)!
Osmosis

Animations for
isotonic, hypertonic,
and hypotonic
solutions
2. Hypertonic Solutions
have a higher concentration of solutes
(dissolved substances) and a lower
concentration of water than inside the
cell
Result: water moves
from inside the cell
into the solution:
cell shrinks
(Plasmolysis)!
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions

Osmosis
animation
Hypertonic Solutions
3. Isotonic Solutions
the concentration of solutes in the
solution is equal to the concentration of
solutes inside the cell.
Result: water moves
equally in both
directions and the cell
remains same size!
(Dynamic Equilibrium)
What type of solution are these cells in?
A
B
C
Osmosis in animal cells
Osmosis in plant cells
Adaptations for Freshwater Protists

paramecium has
contractile vacuoles
that collect water
flowing in and pump
it out to prevent
them from overexpanding.

contractile vacuoles
C. Facilitated Diffusion
D. ( St

diffusion of specific
particles through
transport proteins
found in the membrane
 transports larger
molecules
Channel Proteins
animations
Facilitated Diffusion
II. Active Transport
Requires cellular
energy (ATP)
This is
gonna
be hard
work!!
high
A. Protein Pumps
B. Endocytosis
C. Exocytosis
low
Active Transport
used to transport large molecules
through a membrane
–or to move molecules against the
concentration gradient (low→ high
concentration)

A. Protein Pumps
Example:
Sodium / Potassium
pumps are
important in nerve
responses.
Sodium
Potassium Pumps
(Active Transport
using proteins)
Protein changes
shape to move
molecules: this
requires energy!
B. Endocytosis

forming vacuoles to bring molecules into
a cell
1. Phagocytosis
“cellular eating”
pseudopods (false limbs) are
formed
cell membrane and cytoplasm extend
outward to engulf a large particle
Phagocytosis
2. Pinocytosis
“cell drinking”
 plasma
membrane takes
in particles
dissolved in fluid
when cell
membrane forms
small channels

C. Exocytosis
vacuole moves to the
plasma membrane and
fuses with it to spill
contents outside of cell
•Animations of Active Transport & Passive Transport