Transcript Passive Transport - Hrsbstaff.ednet.ns.ca

CELLULAR TRANSPORT
What gets in and what gets out?
Passive Transport
• 1- Diffusion - occurs when there is an
unequal concentration of molecules on
one side of the cell compared to the other.
The molecules move from the area of high
concentration to an area of lower
concentration until a dynamic equilibrium
is reached.
• USED BY: Small Hydrophobic
Molecules: O2 ,CO2, N2
• activity
Diffusion
Passive Transport
• 2 – Osmosis - the diffusion of water through a
selectively permeable membrane. The
membrane is permeable to water, but
impermeable to the larger molecules. Water
diffuses from an area of high water
concentration to an area of lower water
concentration until the equilibrium between
water and solute is reached.
• USED BY: H2O
• demo
Passive Transport
• 3 - Facilitated diffusion – Gatekeeper
proteins open and close paths through the
cell membrane allowing some molecules
to pass freely. It allows materials to move
in and out of the cell much more quickly
than regular diffusion and does not require
energy from the cell.
• USED BY: Glucose. Diffuses into red
blood cells faster than other similar
sugars.
Active Transport
• The movement of materials from an area
of lower concentration to an area of
higher concentration by expending energy
is called active transport.
• Carrier proteins receive energy that allows
them to aid in active transport.
Active Transport
• 1 – Transport Carrier Proteins – Proteins
open and close paths through the cell
membrane allowing some small solutes to
pass through. Energy is required to
transport the solutes against the
concentration gradient.
• USED BY: Sodium-potassium pump
Animation and quiz
http://highered.mheducation.com/sites/0072495855/student_view0/cha
pter2/animation__how_the_sodium_potassium_pump_works.html
Active Transport
• 2 – Endocytosis – the process by which
cells ingest materials.
• Large molecules can not pass through the
cell membrane.
• The particle pushes against the membrane
and forms an indentation. The cell
membrane wraps around the particle and
engulfs it into a vacuole.
• Often enzymes from lysosomes are then
used to digest the molecules.
Active Transport
• 3 – Exocytosis – the process by which
large molecules in the cell are transported
to the external environment.
• Materials are contained in vesicles. The
vesicles fuse with the membrane and then
the material is released.
• USED BY: waste materials released from
the cell. Transmitter chemicals emitted
from nerve cells.
Organizer
• Make a chart to organize the following key
terms:
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Cellular transport
Diffusion
Osmosis
Facilitated diffusion
Active transport
Endocytosis
Transporters
Passive transport
Exocytosis
Questions
1. Why are cell membranes a “bilayer”?
2. Why are proteins important for the functioning
of a cell? Provide examples
3. Why are cells so small?
4. Compare and contrast:
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Passive Active transport
Diffusion Facilitated Diffusion
Diffusion and Osmosis
5. Why must tissues used in medical procedures
be bathed in a solution of the same osmolarity
as the cytoplasm?
Reference images
• http://faculty.southwest.tn.edu/rburkett/GB
1-osmosis.htm