Cellular Transport
Cellular Transport involves the
Cell Membrane!
• PASSIVE TRANSPORT
• ACTIVE TRANSPORT
– Energy not required
– Energy REQUIRED!
•DIFFUSION
•ENDOCYTOSIS
•OSMOSIS
– Carrier
– Hypertonic
Mediated
– Hypotonic
– Phagocytosis
– Isotonic
– Pinocytosis
– Osmoregulation
•EXOCYTOSIS
•FACILITATED
DIFFUSION
–Passive Transport = Energy not
required.
1. Diffusion = molecules move from
an area of high concentration to an
area of low concentration.
Diffusion is the driving force
behind the movement of
many substances across the
cell membrane.
More on diffusion
• http://www.youtube.com/watch?v=STLAJH
7_zkY
Diffusion will occur IF:
A.There is a concentration
gradient across the cell
membrane.
B. Solution or membrane is
permeable.
NOTE! The cell membrane is semipermeable, which means only small
molecules or fat soluble molecules
can pass across the membrane
without help.
Permeable: It can pass.
Impermeable: Cannot pass.
2nd Type of Passive Transport:
Osmosis: The diffusion of water
across the cell membrane.
How does water
know whether
to move into or
out of a cell?
Hypertonic solution: The solution with
the higher concentration of solutes.
Hypotonic solution: The solution with
a lower solute concentration.
•Isotonic solution: Solutions of
equal concentration of solutes.
Egg Cell in hypertonic vs.
hypotonic solution
• http://www.youtube.com/watch?feature=en
dscreen&NR=1&v=SSS3EtKAzYc
3rd Type of
Passive Transport:
3. Facilitated Diffusion: Molecules
are transported across the cell
membrane by a carrier protein.
Ex.
Glucose is
carried into a
red blood cell
by a carrier
protein.
Cell Survival Depends on the Proper
Balancing of Water Uptake and Loss
•Animals that live in hypo- or
hypertonic environments must
have adaptations for
osmoregulation.
•The protist Paramecium
has a contractile vacuole
that pumps water out as
it enter.
Paramecium – vacuole pumping
out water
• http://www.youtube.com/watch?v=pahUt0R
CKYc&feature=related
•
•The cells of plants, prokaryotes,
and fungi have cells walls, which
keeps the cell from bursting.
•A cell is turgid (firm) when the
back pressure of the cell wall
on the cell opposed any further
water uptake.
•A cell is flaccid (limp) when its
surroundings are isotonic and
there is no net tendency for water
to enter the cell.
Active Transport
•Essential in the ability of a cell to
maintain internal concentrations of
small molecules.
It is the pumping
of molecules
against their
gradients.
ATP supplies
the energy.
Sodium-Potassium Pump
exchanges Na+ for K+ across the
plasma membrane of an animal cell.
https://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodiu
m_potassium_pump_works.html
•All cells have electrical potential
energy (voltage) across their
plasma membranes. This is called
a membrane potential.
•The inside of a cell is ---, and the
outside is +, which causes the
membrane to favor the passive
transport of cations into the cell.
ACTIVE TRANSPORT
1. Endocytosis = The cell membrane
surrounds and engulfs large
particles.
1. Carrier Mediated Endocytosis =
involves carrier proteins on membrane
2. Phagocytosis = Cells bring in large, solid
particles (“cellular eating”)
3. Pinocytosis = Cells take up liquid.
(“cellular drinking”)
Carrier Mediated Endocytosis
Phagocytosis (Endocytosis)
Pinocytosis (Type of Endocytosis)
2. Exocytosis =
Cells remove
large particles.
Exocytosis
The End