Cell transport involves the movement of materials into and out of cells via the cell membrane. There are two main types of transport - active transport which requires energy, and passive transport which does not. Passive transport includes diffusion, osmosis, and facilitated diffusion. Diffusion is the movement of molecules from high to low concentration areas. Osmosis is the diffusion of water across membranes, moving from high to low water concentration. Facilitated diffusion uses carrier proteins to transport molecules across membranes.

1. Cell Transport

2. Cell Transport
• movement of materials (CO2, O2, H2O,
glucose, proteins, etc) into or out of cell via
cell membrane

3. 2 Types of Cell Transport
1. Active Transport- requires energy
2. Passive Transport- No energy required

4. Why is Cell Transport Important?
• Homeostasis- maintaining a steady state
• Metabolism- chemical reactions that
convert “food” into energy
Helps cells achieve equilibrium- when
concentrations of molecules of a
substance are the same everywhere

5. Brownian Motion
• All matter is made up of atoms or
molecules and these particles are
constantly moving. These atoms move in
a straight line until they collide with
another atom or some barrier then they
reflect and move in a straight line until they
collide with something else. This
movement of atoms and molecules is
called Brownian motion.

6. 3 Types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated Diffusion

7. 1. Diffusion
• movement of molecules from areas of
higher concentration to areas of lower
concentration
• requires no energy expenditure by cell

8. Key components of cell that
function in cell transport
• Cell membrane- phospholipids bilayer
• Cytoplasm- aqueous solution that contains
materials
• Mitochondria- powerhouse of cell
(glucose ATP)
• RBC- carries protein hemoglobin that
transports oxygen and carbon dioxide to
and from cells

9. Example of Cellular Diffusion

10. Review
• Solution= Solute + Solvent
• Solute
• Solvent
Ex: Sugar water
Salt water

11. 3 Prefixes for SOLUTES
• Hypo = Low Ex: Hypothermia,
hypoglycemic
• Hyper = High Ex: Hyperactive,
hyperglycemic
• Iso = Equal

12. Solution Types
1. Hypotonic Solution- concentration of
solute molecules outside the cell is lower
than the concentration in cytosol (water
moves into cell until equilibrium is
reached)

13. Solution Types
2. Hypertonic Solution- concentration of
solute molecules outside the cell is higher
than the concentration in cytosol (water
moves out of cell until equilibrium is
reached)
• water tends to diffuse from hypo- to
hypertonic solutions

14. Solution Types
3. Isotonic Solution- concentration of solute
molecules outside and inside the cell are
equal ( water moves in and out of cell but
at equal rates)

15. 2. Osmosis
• process by which water molecules diffuse
across a cell membrane from an area of
higher concentration to an area of lower
concentration
• Requires no energy expenditure by cell 
Passive Transport

16. Extreme Osmosis
• Concentration gradient is so far from
equilibrium that even after moving water
or solutes, equilibrium still will not be
reached, and this may result in DEATH
of cell
1. Crenation- dehydration of an animal cell
2. Plasmolysis- dehydration of a plant cell
3. Cytolysis- cell bursting, usually occurs in
animal cells

17. Plant Cells and Osmosis
• Plant cells- usually in a hypotonic
environment
• Water moves into cell via osmosis
• Cell expands until it presses against cell
wall, creating a pressure called turgor
pressure

18. 3. Facilitated Diffusion
• Proteins embedded in cell membrane help
molecules that can’t move across membrane
rapidly enough, into or out of cell
• Carrier proteins are specific for one type of
molecule
• Protein changes shape protecting molecule from
hydrophobic interior of membrane, then releases
molecule on other side

19. Ion Channels
• similar to carrier proteins, but are specific
for certain ions
• Examples of ions: Na+, Cl-, K+, Ca+2
• These ions are important for many cell
functions, but are not soluble in lipids so
need to pass through these ion channels
• Some channels are always open, others
close

20. Active Transport
• movement of materials up concentration
gradient from areas of lower concentration
to areas of higher concentration
• requires cells to use energy
• works like proteins in facilitated diffusion
(bind to specific molecule, changes shape
to protect, and releases molecule on other
side)

21. • Ex: Sodium/Potassium Pump
• Many animal cells need higher Sodium
concentration outside of cell and higher
Potassium concentration inside cell
• Splits molecule of ATP to change shape of
protein to allow this

22. 2 Types of Active Transport
1. Endocytosis-process by which cells
ingest external fluid, macromolecules,
and large particles, including other cells
• enclosed by portion of cell that folds in
on itself creating a pouch called a vesicle

23. 2 Types of Endocytosis
A. Pinocytosis- “cell drinking” –involves
transport of solutes or fluids
B. Phagocytosis- “cell eating” –movement
of large molecules or whole cells into a
cell
*animal cells ingest bacteria and destroy
them via phagocytosis

24. • 2. Exocytosis-vesicles in cytoplasm fuse
with cell membrane releasing contents into
external environment
• *Remember this is how proteins leave cell
• Nervous and endocrine systems use
exocytosis to release small molecules that
control activities of other cells