1. Cell Transport
CELLS Unit 4
PPT#3

2. What do cells do with the energy they make in cellular Respiration?

3. A lot of ATP are needed to maintain homeostasis (happiness) within the cell!!
Cells need to get rid of things AND they need to bring in things…..some is easy and no energy needed…some are harder and the cell needs to “spend” energy!

4. 2 concepts that make Cell Transport possible
Structure of cell membranes
Selectively Permeable Cell Membrane
ALL cells have a cell membrane made of
phospholipids and proteins
2. A Concentration Gradient

5. Function of the Cell Membrane:
Cell membrane separates the components of a cell from its environment—surrounds the cell
“Gatekeeper” of the cell—regulates the flow of materials into and out of cell—selectively permeable
Cell membrane helps cells maintain homeostasis—stable internal balance

6. Selectively Permeability:
A property of biological membranes that allows some substances to cross the membrane more easily than others.
Concentration gradient: The difference in the amount of solution on each side of a cell membrane

7. Cell membranes are made of Phospholipid bi-layer
Hydro: Water
Philia: Love
Phobia: Fear or hate
HEAD: LOVES WATER hydrophilic
TAIL: HATES WATER hydrophobic
Heads out, tails in…
the membrane forms a bi-layer (2)

8. Types of Cellular Transport
Passive Transport
NO ENERGY
Diffusion
Facilitated Diffusion
Osmosis
Active Transport
NEEDS ATP!!
Carrier Proteins pumpp in materials agaiinst gradient
Endocytosis
Exocytosis

9. Passive transport
Diffusion: substances move from an area of high conc. to an area of low conc. across a membrane in which the cell expends no energy.
(sliding down a slide)
Oxygen, CO2, small molecules and ions

10. Facilitated Diffusion: the process of transporting molecules by channel proteins during diffusion, requires no energy output (someone else carrying you down the slide)
EX: Glucose
Sodium and
Potassium

11. Osmosis is the diffusion of water through a selectively permeable membrane like the cell membrane
Water diffuses across a membrane from an area of high concentration to an area of low concentration.

12. Osmosis is facilitated by channel proteins in the phospholipid bi-layer called Aquaporins.

13. Active transport Needs: Energy!
Transport of molecules against a concentration gradient (from low conc. to high conc.) using carrier proteins in the cell membrane and energy from ATP.
(walking up the slide)
EX: Polysaccharides,
large and small molecules

14. How Does that Look in a Cell?
A: Passive Diffusion
B: Facilitated Diffusion (needs channel protein)
C: Active Transport
(needs ATP & carrier protein)

16. 2 moreTypes of Active Transport
Endocytosis
The bringing of materials into cell (eating)
Exocytosis: The release of materials to the outside of the cell (pooping)

17. Cell Size and Diffusion
Cells must remain small to maximize diffusion
The larger a cells volume becomes, the less efficient it becomes.
Prokaryotes - Limited by efficient metabolism
Animal Cells (Eukaryotic) - Limited by surface area to volume ratio
Surface area of cells must be proportionally larger than it’s size (volume)

18. SOLUTIONS Solvent: a liquid that dissolves the solute, usually water or alcohol Solute: Anything dissolved in a solvent Together they make a Solution
Salt Water + =

19. This is why you get thirsty after eating something salty.
A simple rule:
Salt Sucks!
When salt is inside or outside the cell, it draws water in its direction.
This is why you get thirsty after eating something salty.
Same thing applies for all other solutes

20. Solutions and Cells
All solutions want to be equal on both sides of the membrane for homeostasis.
Substances dissolved in solution have special vocabulary to describe them
Hypertonic
Hypotonic
Isotonic

21. Hypertonic
The conc. of solute outside the cell is higher than the conc. inside
The solution outside is hypertonic
Water diffuses out of the cell until equilibrium is established.
The cell will shrink and lose mass

22. Hypotonic
The conc. of solute outside the cell is lower than the conc. inside
The solution outside is hypotonic
Water diffuses into the cell until equilibrium is established.
The cell will get bigger and gain mass

23. Isotonic The conc. of solute outside and inside the cell are equal
The solution outside is isotonic
Water diffuses into and out at equal rates
No net change in size or mass

24. Higher water conc inside cell Water moves out Cell Shrinks
Isotonic
Hypotonic
Hypertonic
H2O
CHO
Higher water conc inside cell
Water moves out
Cell Shrinks
Higher water conc outside the cell
Water moves in
Cell Swells
Water moves in and out
Cell Size remains same
In this situation, glucose is toooo BIG to get through the membrane.