April 20, 2023
Cell Membrane Transport Notes
I.) Types of Cell Membrane Transport
There are 2 types of cell membrane transport:
A. Passive Transport1. Things flow fromHigh to low
B. Active Transport1. Things flow from Low to high
Passive & Active Transport
II.) Passive Transport
A. Diffusion1. Definition: The movement of particles from
areas of high concentration to low concentration
http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html
2. Equilibrium
a. Continuous movement of particles, but no change in concentration
b. When is equilibrium reached when discussing cell membrane transport?
When the concentrations of particles are the same on both sides
3. Facilitated Diffusion
a. Particles flow from high concentration to low concentration but this time they need the help of proteins to get through the cell membrane.
Passive transport (cont.)
B. Osmosis1. The diffusion of water across a selectively
permeable membrane2. Important in maintaining cell homeostasis3. Water flows to side of membrane where the water
concentration is lower until equilibrium is reached
Osmosis (cont.)
4. Osmosis is controlled by the amount of solutes on either side of a membrane
Remember, this is important, Osmosis deals with what?
The
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1. The movement of particles
2. The movement of glucose
3. The movement of water
4. The movement of lipids
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Osmosis – Types of Solutions
When dealing with osmosis, water can either move into the cell or out of it.
We describe the solutions that cells are in as either hypotonic, isotonic, or hypertonic.
What are the concentrations?
90%
40%
Isotonic Solution
Isotonic solution – Concentration of solute is the same in the cell and the area around the cell.
Isotonic solution
Hypotonic Solution
Hypotonic Solution – Concentration of solute is lower in the solution than in the cell.
Where is water going to move in order to reach equilibrium (Equal concentrations)? Inside the cell
Hypotonic solutions
Since water moves into the cell the cell can explode
So, Hypotonic solution, low concentration of solute, cell can explode
Plant & animal cells in a hypotonic solution
Hypertonic Solution
Hypertonic solution – concentration of solute is higher in the solution than in the cell.
Where is water going to move in order to reach equilibrium (Equal concentrations)? Outside the cell
Hypertonic solutions
Since water moves out of the cell the cell will shrink
So, Hypertonic solution, high concentration of solute, cell will shrink
Plant & animals cells in a Hypertonic Solution
The following diagram demonstrates what type of solution?
Hyp
oton
ic
Isoto
nic
Hyp
erto
nic
0% 0%0%
= solute
1. Hypotonic2. Isotonic3. Hypertonic
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In the following diagram which way is water going to move?
Insi
de th
e ce
l...
Outs
ide
of the.
..
Both
1 a
nd 2
0% 0%0%
= solute
1. Inside the cell2. Outside of the cell3. Both 1 and 2
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The following diagram demonstrates what type of solution?
Hyp
oton
ic
Isoto
nic
Hyp
erto
nic
0% 0%0%
= solute
1. Hypotonic2. Isotonic3. Hypertonic
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In the following diagram which way is water going to move?
Insi
de th
e ce
l...
Outs
ide
of the.
..
Both
1 a
nd 2
0% 0%0%
= solute
1. Inside the cell2. Outside of the cell3. Both 1 and 2
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Active Transport
Molecules move from low concentration to high concentration Requires energy….why?
Other membrane transport activities that require energy
Endocytosis Engulfing of large particles or liquids from outside the
cell
2 types of Endocytosis
Phagocytosis Engulfing of large particles from outside the cell
Pinocytosis Engulfing of liquids from outside the cell
Other membrane transport activities that require energy
Exocytosis Release of large particles or liquids from inside the cell
Inside the cell
Outside the cell
This diagram is an example of what membrane transport?
Diff
usion
Fac
ilita
ted
di...
Endoc
ytosi
s
Exo
cyto
sis
0% 0%0%0%
1. Diffusion2. Facilitated
diffusion3. Endocytosis4. Exocytosis
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This diagram is an example of what membrane transport?
Diff
usion
Fac
ilita
ted
di...
Endoc
ytosi
s
Exo
cyto
sis
0% 0%0%0%
1. Diffusion2. Facilitated
diffusion3. Endocytosis4. Exocytosis
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