Cell Membrane
Transport
Cell membrane transport

There are 2 types of cell membrane
transport:

Passive Transport
Substance move from
High concentration to
low concentration
-no energy required


Active Transport
Substance move from
low concentration to
high concentration
-energy (ATP) required

Another perspective on
passive and active transport
Passive Transport

Diffusion

The movement of particles from areas of high
concentration to low concentration
Diffusion

Factors that influence the rate of
diffusion
Temperature
 Pressure
 Electrical currents
 Molecular size

Equilibrium

the concentrations of particles are the same
on both sides of the membrane
Facilitated Diffusion

Particles flow from high concentration to
low concentration but this time they need
the help of proteins to get through the cell
membrane.
Facilitated diffusion
Osmosis



The diffusion of water across a selectively permeable
membrane
Important in maintaining cell homeostasis
Water flows to side of membrane where the water
concentration is lower until equilibrium is reached
Osmosis

Osmosis is controlled by the amount of
solutes on either side of a membrane
Osmosis – Types of Solutions
 When
dealing with osmosis, water can
either move into the cell or out of it.
 The solute cannot move to equal out the
concentration of solutions, so the water
has to.
 We describe the solutions that cells are
in as either hypotonic, isotonic, or
hypertonic.
Isotonic Solution

Isotonic solution – Concentration of
solute is the same in the cell and the area
around the cell.
Water moves in and out at equal rates.
Isotonic solution
Hypotonic Solution

Hypotonic Solution – Concentration of
solute is lower in the solution than in the
cell.

Net movement of water INTO the cell.
Hypotonic solutions

Since water moves into the cell the cell,
animal cells can explode

Cytolysis
Plant and animal cells in a
hypotonic solution
Turgor Pressure – central
vacuole is full; pressure against
the cell wall
Hypertonic Solution

Hypertonic solution – concentration of
solute is higher in the solution than in the
cell.

Net movement of water OUT of the cell.
Hypertonic solutions

Since water moves out of the cell the cell
will shrink
Plant and animals cells in a
Hypertonic Solution
Plasmolysis: shrinking of cytoplasm due to osmosis
Active Transport

Molecules move from low concentration
to high concentration

Requires energy….why?
Active Transport

Molecular Transport

Protein Pumps
 Small
molecules and ions carried across
the cell membrane by proteins in the
membrane that act like pumps (low 
high)

Bulk Transport
Endocytosis – in!
 Exocytosis – out!

Sodium Potassium Pump
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

Inside
the cell
Release of large particles or liquids from
inside the cell
Outside
the cell
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1.
Which of the following allows cells to
recognize each other as self or
foreign?
Channel Proteins
Cholesterol
Phospholipids
Glycoproteins
10
The inside of the cell
membrane consists of
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Phosphate heads
Fatty acid tails
Extracellular
Matrix
Carbohydrate
chains
Ph
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Which of the following components of the
cell membrane affects the fluidity of the
cell membrane?
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Glycoproteins
Glycolipids
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Extracellular
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Which type of protein is responsible
for receiving messages from
hormones?
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Channel protein
Carrier protein
Cell Recognition
Protein
Receptor Protein
Ch
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1.
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The movement of particles from high
concentration to low concentration is
called
to
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Osmosis
Diffusion
Endocytosis
Exocytosis
Os
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The diffusion of water is
called
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Active transport
Endocytosis
Exocytosis
Osmosis
Ac
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The movement of particles
across a membrane that requires
energy (ATP) is called
...
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Passive transport
Active transport
Aquaporins
Semi-permeable
Pa
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1.
10
This diagram is an example
of what membrane transport?
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Diffusion
Facilitated
diffusion
Endocytosis
Exocytosis
D
1.
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This diagram is an example
of what membrane transport?
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Diffusion
Facilitated
diffusion
Endocytosis
Exocytosis
D
1.
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