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Transport in the Cell
In a way a cell is like a miniature version of you. It requires nutrients and, in the process of breaking down
the nutrients, the cell produces wastes. So there has to be a way to
get nutrients in and wastes out.
One particular part of the cell plays a huge role in controlling what enters and leaves the cell, so this organelle
is in charge of CELLULAR TRANSPORT.
Cell Membrane PhospholipidsPhospholipids – main
component of the cell membrane
Cholesterol Cholesterol – prevents close packing of the lipids
Proteins Proteins – transport ions through the membrane
General TermsConcentration Gradient –The unequal distribution of particles
Concentrations
Cell Transport2 Main Types of Transport:
Passive Transport
Active Transport
No Energy Needed
Molecules naturally want to reach a balance on either side of a membrane moving from
high to low concentration
“Homeostasis”
The cell’s version of energy is needed - ATP
It moves molecules from low concentration to high
concentration.
Cell TransportPASSIVE TRANSPORT
DIFFUSION
The movement of molecules from a
HIGH to LOW concentration
http://www.stolaf.edu/people/giannini/flashanimat/transport/diffusion.swf
Cell TransportPASSIVE TRANSPORT
OSMOSIS
the diffusion of water
http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf
Cell TransportPASSIVE TRANSPORT
FACILITATED DIFFUSION
“needs a passageway”
More General Terms Osmotic PressureOsmotic Pressure – the
water pressure in cells Turgor pressureTurgor pressure – the water
pressure in plant cells Plasmolysis Plasmolysis – Process
where the cell membrane pulls away from the cell wall due to water loss
Solutions
Passive Transport
0 % solutes
75% solutesSolutes:Dissolved
substances like salt
and sugar.
1. Where is the concentration of solutes the greatest?
2. Where is the concentration of water the greatest?
3. Which molecule would be easier to move – the solute or the water?
Passive Transport
0 % solutes
75% solutes
As a result, the smaller molecule, water, will
move into the cell causing the cell to expand.
75% solutes
Passive Transport
0 % solutes
75% solutes
Since the concentration of the solutes OUTSIDE of the cell is
lower, then the solution is considered to
be HYPOTONIC.
Outside the cell
Solutes
Passive Transport
50 % solutes
50% solutes
As a result, the smaller
molecule, water, will move into and out of the cell at an equal rate causing the
cell to remain the same size.
Passive Transport
50 % solutes
50% solutes
Since the concentration of the solutes OUTSIDE of the cell is
EQUAL or the SAME, then
the solution is considered to be ISOTONIC.
Outside the cellSolutes
Passive Transport
70 % solutes
20% solutes
As a result, the smaller molecule, water, will move outout of
the cell causing the
cell to shrivel.
20%
Passive Transport
70 % solutes
20% solutes
Since the concentration of
the solutes OUTSIDE of the
cell is HIGHER or ABOVE, then the
solution is considered to be
HYPERTONIC.
Outside the cellSolutes
Everyday examples of solutions
Hypertonic: Alcohol, Caffeine, Ocean water, Epson Salt bath
Hypotonic: Distilled waterIsotonic: Blood
Cell Transport
Active transportIt moves molecules from low concentration
to high concentration.
Cell Transport
Why does active transport need energy?
Because the molecules are moving against against the CONCENTRATION GRADIENT.
Cell TransportSometimes a substance that a cell needs to transport in is too large to fit through the cell membrane, so the membrane moves
around the substance.
Endocytosis - the cell membrane
engulfs a substance by surrounding it
and forming a “vessicle.”
Exocytosis – The cell needs to rid the cell of a waste or substance so it forms a “vessicle” around it and releases the substance at the cell
membrane.
Cell Transport
50 % solutes
50% solutes
50 % solutes
0% solutes
50 % solutes
100% solutes
80 % solutes
90% solutes
100 % solutes
10% solutes
