1. By: Diana Bivens Modified by: Kerri Shrestha
CELLULAR TRANSPORT
By: Diana Bivens
Modified by: Kerri Shrestha

2. Plasma Membrane Plasma membrane:
a selectively permeable membrane that surrounds all cells
Maintains cellular homeostasis

3. Plasma Membrane Plasma Membrane
Hydrophilic (water-loving) heads make up the outer layers of the bilayer
Hydrophobic (water-hating) tails make up the inner layers of the bilayer

4. Plasma Membrane
The structure ensures that water does NOT pass freely through it
Water CAN pass through a process called osmosis
“osmos”: pushing

5. Diffusion & Osmosis Diffusion: Osmosis: the diffusion of
the movement of
particles from an area of
high concentration to an
area of low concentration
Osmosis: the diffusion of
water across a selectively
permeable membrane

6. How does osmosis work?
Water will move across a selectively permeable membrane down a concentration gradient.
animationl

7. Water will continue to move until the environment within the cell is in balance with the environment outside the cell
Dynamic Equilibrium:
When the solutions on both sides of the membrane are equal but water continues to move (no net change)

8. How does osmosis work? Cells and isotonic solutions
Isotonic solution: the concentration of dissolved substances is the same on both sides of the cell membrane

9. Cells in isotonic solutions retain their shape

10. How does osmosis work? Cells in hypotonic solutions
Hypotonic solution: the concentration of dissolved substances is lower outside the cell

11. Cells in hypotonic solutions
cells try to maintain a balance with the solution outside. The cells will…
SWELL

12. How does osmosis work? Cells in hypertonic solutions
Hypertonic solutions: the concentration of dissolved particles is greater outside than inside the cell

13. Cells in hypertonic solutions
Cells will try to maintain balance with their surroundings and they will…
SHRINK!

14. Hypo or Hyper
Hypo or Hyper

15. balloon demo

16. Passive Transport
Passive transport: When cellular energy is not required to move substances along a concentration gradient
High concentration to low concentration

17. Passive Transport Facilitated diffusion
Particles are too large to diffuse through the plasma membrane
Uses the aid of transport proteins
Sugars
Amino acids
facilitated diffusion animation

18. PASSIVE TRANSPORT
Examples
Osmosis
Facilitated diffusion

19. Examples of Osmosis in Living Cells
Turgor pressure
in plants
Death of bacterial cells as a result of the processes of food preservation
Human red blood cells when the human body is dehydrated

20. How do cells regulate their amount of water uptake?
The plant cell has a cell wall
One celled organisms have a contractile vacuole that pumps out excess water
Animals excrete water through urine and sweat

21. Active Transport
Active transport: when a cell uses energy to move particles AGAINST a concentration gradient
______ concentration to ______concentration
Low
High

22. Active Transport
carrier proteins bind to and transport the substance across the plasma membrane against the gradient

23. Active Transport of Large Molecules
Endocytosis: cell surrounds a substance and engulfs it

24. Active Transport of Large Molecules
Exocytosis: a cell expels or secretes a substance
Expels waste
Secretes hormones

26. Cell Size Why are cells so small?
Diffusion is more efficient in a small cell
DNA in the nucleus must support all protein needs of the cell in a timely manner
A cell requires enough surface area to allow an adequate amount of substances to enter and exit the cell (as a cell grows, its surface area-to-volume ratio decreases drastically)