1. Transport Conclusion

2. Review
Many substances enter the cell through protein channels. Some of these channels require energy (ATP) to work

3. Review Active Transport
Often material moves across a cell membrane against concentration difference.
Moves from an area of lower concentration to an area of higher concentration
Requires ENERGY (ATP)

4. Active Transport Active transport is often compared to a pump
Requires ATP
Moving from lower concentration higher conc.

5. Example: Sodium Potassium Pump
Na+ High
K+ Low
Active Transport
because:
Ions move from low to high
Requires ATP
Na+ Low
K+ High
Sodium Potassium Pump

6. Other Types of Active Transport
Endocytosis
Phagocytosis
Pinocytosis
Receptor-Mediated
Exocytosis

7. Other types of Active Transport: Moving the BIG stuff
Macromolecules (proteins; polysaccharides; nucleic acids) are TOO LARGE to cross the plasma membrane
They can be moved by means of vesicles

8. Moving the BIG stuff IN Endocytosis
Process that brings molecules and cells into a eukaryotic cell
Plasma membrane folds in around the material, forming a vesicle

9. Endocytosis: Phagocytosis
Molecules or entire cells are engulfed
A food vacuole is formed

10. Phagocytosis
- Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)

11. Endocytosis: Pinocytosis
Most common form of endocytosis
Takes in dissolved molecules as a vesicle (smaller than phagocytosis)

12. Receptor-Mediated Endocytosis
The Plasma Membrane
2/22/2019
Receptor-Mediated Endocytosis
Some proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc.

13. Receptor-Mediated Endocytosis
The Plasma Membrane
2/22/2019

14. Moving the BIG stuff OUT Exocytosis
Molecules (indigestible materials; digestive enzymes; neurotransmitters) are moved out of the cell by vesicles that fuse with the plasma membrane

15. Exocytosis
Exocytic vesicle immediately after fusion with plasma membrane.

16. Exocytosis
Endocytosis and Exocytosis
Inside the cell
Outside the cell

17. Let’s Review 3 Types of Passive Transport 3 Types of Active Transport
Diffusion
Osmosis
Facilitated Diffusion
3 Types of Active Transport
Active Pump
Endocytosis
Exocytosis

18. Passive Transport

19. Active Transport

20. Lead
Lead, which is positively charged, cannot diffuse into the cell and is actively transported via an energy dependent protein channel
Why would a cell take up something that is poisonous?

21. Why would a cell take up something that is poisonous?
Both lead and calcium are charged and have a similar charge value (+2)
Lead and calcium are found in the same tissues
Bones, teeth, nerves
Lead is transported via the calcium channel pump because it is similar in structure and charge to calcium ions
The body “mistakes” lead for calcium!