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Cellular Transport
Chapter 7.4
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Cell Transportation
• Materials needed for cellular processes
must pass into cells so they can be
utilized.
• Waste materials from cellular processes
must pass out of cells as they are
produced.
The Plasma Membrane
• Regulates the passage of
material into and out of the cell.
• Depending on the needs of the
cell, substances will move
either in or out of the cell.
• Because cells exist in a fluid
environment, it is possible for
substances to move in and out
of the cell.
Homeostasis
• The necessity of an organism to
maintain a constant or stable condition.
• Dependent on appropriate movement of
materials across the cell membrane.
• All organisms have processes and
structures which respond to stimuli in
ways that keep conditions in their
bodies conducive to life.
Homeostasis
• Maintained by the cell membrane.
• The cell membrane is selectively
permeable (semipermeable).
• Materials can enter or exit the cell
membrane by passive or active
transport.
Homeostasis
• How do our cells
maintain homeostasis?
• 1)Passive Transport
• 2)Active Transport
http://nestbio.blogspot.com/2010/11/passive-and-active-transport.html
Concentration Gradients
• Molecules move in expected ways
based on their concentration gradient.
• At equilibrium, the concentration
gradient is the same on both sides, so
their is no movement.
Passive Transport
• Movement of any substance through
the cell membrane.
• Controlled by the cell membrane.
• Does not require the use of energy.
• Substances move with the
concentration gradient.
• HIGH TO LOW GO WITH THE FLOW
Passive Transport:
Diffusion
• Process by which molecules spread across a
cell membrane to reach an equal
concentration (equilibrium).
• Slow process dependent on concentration,
temperature, and pressure.
• Movement of small ions, atoms, gases, and
molecules.
• HIGH TO LOW GO WITH THE FLOW
Diffusion
• How Diffusion Works Animation
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_
diffusion_works.html
Passive Transport:
Osmosis
• The diffusion of H20 through a
selectively permeable membrane.
• Water will move in and out of the cell
until it reaches equilibrium.
• Dependent on the concentration
gradient.
• HIGH TO LOW GO WITH THE FLOW
Osmosis
• How Osmosis Works Animation
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_
osmosis_works.html
Passive Transport:
Facilitated Diffusion
• Substances that are not able to pass
directly through the cell are able to
enter the cell with the aid of transport
proteins.
• Occurs along a concentration gradient.
• Ex) Glucose
Facilitated Diffusion
Proteins
• Integral
• Peripheral
• Channel
• Carrier
• Marker
• Receptor
• Symports
http://www.clker.com/clipart-49540.html
Facilitated Diffusion
• How Facilitated Diffusion Works
Animation
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_f
acilitated_diffusion_works.html
Solutions
Kool Aid Packet
Solute
Solvent
Water
Kool Aid Drink
Solution
Isotonic Solutions
http://imcurious.wikispaces.com/Midterm+Exam+2010+Review+P2
Hypotonic
http://spmbiology403.blogspot.com/2008/08/types-of-solution-hypotonic.html
Hypertonic
http://spmbiology403.blogspot.com/2008/08/types-of-solution-hypertonic.html
Solutions
http://biologyforlife.wordpress.com/2011/03/25/3-2-the-movement-of-substances-across-the-plasma-menbrane-in-everyday-life/
Active Transport
• Cells pump molecules through the cell
membrane and require energy.
• Molecules move across the cell membrane
against the concentration gradient (low to
high).
• Cells use this process to concentrate
molecules within the cell or to remove waste
from the cell.
• Ex) Calcium, Sodium, and Potassium ions
Active Transport:
Proton Pump
• Causes production of
ATP molecules
(energy).
• Actively transports
proteins through the
membranes of
mitochondria and
chloroplasts.
http://bioap.wikispaces.com/Ch+7+Collaboration+2010
Active Transport:
+
+
Na /K Pump
• Uses ATP to transport
Na and K into and out of
the cell.
• Nerve cells use the
difference in ion
concentrations to send
signals throughout your
body.
http://163.16.28.248/bio/activelearner/05/ch5c4.html
Active Transport:
Endocytosis and Exocytosis
• When molecules are too large to pass
through the cell membrane, the use of
vesicles is required.
• If the large molecule is passing into the
cell it is called endocytosis.
• If the large molecule is passing out of
the cell it is called exocytosis.
Endocytosis and Exocytosis
http://thescienceupdate.blogspot.com/2010/09/may-force-be-with-you.html