1. Cellular Transport Processes
The Plasma Membrane, Solutions, and Movement of Materials

2. Homeostasis
Homeostasis is the maintaining the same internal state when the external is changing.
Example – Sweating maintains proper body temperature.

3. Homeostasis & the Cell Membrane
The cell membrane maintains cell homeostasis by being semi-permeable.
These are membranes that allow some substances to pass through, but not others.

4. Homeostasis & Cell Membrane
Why?
Cells to get rid of wastes while keeping other molecules in.
Endocytosis – take in or ingest nutrients
Exocytosis – to release or remove waste
Likewise, they must let things in (like nutrients) while keeping others out (like toxins).

5. Endocytosis
Receptor Mediated Endocytosis

6. Endocytosis
Pinocytosis – “cell drinking”

7. Endocytosis
Phagocytosis – “cell eating”

8. Structure of the Cell Membrane
The cell membrane is a phospholipid bi-layer
Phospho = phosphate heads
Hydrophilic – “water loving”
Lipid = fatty acid tail
Hydrophobic – “water scared”
Bi = two

9. Structure of the Cell Membrane
The cell membrane is fluid, not rigid

10. Membrane Proteins
Each layer is made up of a sheet of lipid (fat) molecules with protein molecules embedded in the lipid bi-layers.
Carrier Proteins allow substances that are too large to fit through the bi-layer into the cell
Example – Like raisins in a slice of raisin bread.

12. Diffusion
Movement of particles/ “Stuff” from more concentrated to an area of lesser concentration.
Particles tend to distribute themselves evenly within a solution
Occurs until equilibrium is reached

13. Diffusion An example of diffusion
Spraying perfume in an area. It is very strong in that area at first, and then it spreads out through the room and is not as strong.

14. Types of Diffusion Passive Transport Simple vs. Facilitated Diffusion
No energy
May or may not need a protein

15. Types of Diffusion Active Transport Requires energy - ATP
Requires a membrane protein

16. Osmosis The diffusion of water molecules.
Water molecules moves from an area of high concentration to an area of low concentration.

17. Solutions There are 3 types of solutions:
Hypotonic (“hypo” = below/low)
Hypertonic (“hyper” = excessive)
Isotonic (“iso” = equal)

18. So the water will flow from outside  inside cell
Hypotonic solutions
A solution whose solute concentration is lower than the solute concentration inside a cell
Example: Distilled water
High concentration of water = outside
Low concentration of water = inside
So the water will flow from outside  inside cell

19. So the water will flow from inside  outside
Hypertonic solutions
Are solution whose solute concentration is higher than the solute concentration inside the cell.
Example: Salt Water…the ocean!
High concentration of water = inside
Low concentration of water = outside
So the water will flow from inside  outside
Cell will shrivel.

21. Isotonic solutions
An isotonic solution is a solution whose solute concentration outside the cell is equal to the solute concentration inside the cell.
Cells are in equilibrium
Example: Our blood!