1. Cellular Transport

2. Homeostasis
***Remember the 8 Characteristics of Living Things: maintain a stable internal environment. --Homeostasis: the process by which organisms keep internal conditions relatively constant despite changes in the external environment.

3. (CELL MEMBRANE AND CELL WALL)
What part of the cell helps to maintain homeostasis (control what enters and leaves the cell)?
CELL BOUNDARIES
(CELL MEMBRANE AND CELL WALL)

4. Cell Boundaries
1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer

5. Types of Boundaries
1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer
Functions
Regulates what enters and leaves the cell

6. Types of Boundaries
1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer
Functions
Regulates what enters and leaves the cell
Provides protection

7. Types of Boundaries
1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer
Functions
Regulates what enters and leaves the cell
Provides protection
Provides support

8. Types of Boundaries
1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer
Made up of lipids

9. Types of Boundaries
1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer
Made up of lipids
Have proteins stuck in the membrane

10. 2. Cell Walls Types of Boundaries
Are present in plant cells (fungi and many prokaryotes) but not animal cells

11. 2. Cell Walls Types of Boundaries
Are present in plant cells (fungi and many prokaryotes) but not animal cells
Lies outside of the cell membrane

12. 2. Cell Walls Types of Boundaries
Are present in plant cells (fungi and many prokaryotes) but not animal cells
Lies outside of the cell membrane
Made up of cellulose

13. Types of Boundaries 2. Cell Walls
Are present in plant cells (fungi and many prokaryotes) but not animal cells
Lies outside of the cell membrane
Made up of cellulose
Functions:
Provides protection

14. Types of Boundaries 2. Cell Walls
Are present in plant cells (fungi and many prokaryotes) but not animal cells
Lies outside of the cell membrane
Made up of cellulose
Functions:
Provides protection
Provides support

15. Moving Across Cell Boundaries

16. In a solution particles are moving constantly
Concentration
Cytoplasm of a cell contains a solution of many different substances in water.
Substances dissolved in the water are the solutes
Ex. glucose, Na+, etc.
In a solution particles are moving constantly
Think about the lemonade example

17. Diffusion
Diffusion: molecules move from an area of higher concentration to an area of lower concentration

18. Diffusion
Diffusion: molecules move from an area of higher concentration to an area of lower concentration
Concentration Gradient
Diffusion Animation:

19. Diffusion
Diffusion: molecules move from an area of higher concentration to an area of lower concentration
Concentration Gradient
Equilibrium: when the concentration of the solute is the same throughout the system (there is still movement but at an equal rate)

20. Diffusion
Diffusion: molecules move from an area of higher concentration to an area of lower concentration
Concentration Gradient
Equilibrium: when the concentration of the solute is the same throughout the system (there is still movement but at an equal rate)
Diffusion does NOT require energy

21. Osmosis
When substances are too large to move across the membrane, water may move across the membrane to balance the concentration on either side of the membrane.

22. Osmosis
When substances are too large to move across the membrane, water may move across the membrane to balance the concentration on either side of the membrane.
Osmosis: diffusion of water through a selectively permeable membrane

23. Osmosis
When substances are too large to move across the membrane, water may move across the membrane to balance the concentration on either side of the membrane.
Osmosis: diffusion of water through a selectively permeable membrane
Semi-permeable membrane: allows some substances to cross

24. Passive Transport Diffusion and Osmosis do NOT require energy
They are considered PASSIVE forms of transport
Facilitated Diffusion: movement of specific molecules across cell membranes through protein channels.

25. Active Transport
Sometimes cells must move materials in the opposite direction (against the concentration gradient)
This requires ENERGY
Active Transport