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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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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