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Diffusion, Osmosis & Cell Membrane

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Presentation on theme: "Diffusion, Osmosis & Cell Membrane"— Presentation transcript:

1 Diffusion, Osmosis & Cell Membrane
Section 1.3 Pages 40-52

2 Cell Size Vary in size 10-100μm

3 Why don’t we have giant singled celled organisms running around
WHAT LIMITS CELL SIZE? Why don’t we have giant singled celled organisms running around

4 WHAT LIMITS CELL SIZE? All cells need to exchange food, waste, and gases with their surroundings Limiting factor Surface area to volume ratio

5 SURFACE AREA TO VOLUME RATIo
Surface area: area exposed to outside Volume: stuff in the middle What happens to the surface area and volume when a sphere gets larger???

6 GIANT CELLS DO NOT EXIST
WHAT DOES THIS MEAN? It means that as a cell increases in size its surface area to volume ratio decreases So it is harder for things to Enter Exit GIANT CELLS DO NOT EXIST

7 Largest Single Cell

8 Animal Cell

9 Cell Membrane Cell membrane is selectively permeable
Allows some things to pass through Prevents other things from entering Also called semi-permeable

10 Selectively Permeable
CELL

11

12 Concentration Concentration is the amount of substance in a given space.

13 Dilute vs Concentrated

14 Diffusion

15 does not require energy
Diffusion does not require energy allows for the movement of materials across the cell membrane

16 Diffusion Movement down a concentration gradient
From HIGH concentration to LOW CONCENTRATION

17 Diffusion

18 Diffusion

19 Lab Activity on Diffusion Rates

20 Osmosis A special term that refers to the movement of water only down a concentration gradient

21 Osmosis Osmosis = Diffusion of water across a selectively permeable or semi-permeable membrane

22 Osmosis https://youtu.be/IaZ8MtF3C6M

23 Osmosis

24 Osmosis

25 WS 2-2 Cell Membrane Using your Text Book page Complete Pages 1 to 3

26 Three examples of osmosis: 1
Three examples of osmosis: 1. Equal movement of water in and out = ISOTONIC

27 Three examples of osmosis: 2
Three examples of osmosis: 2. More water moving into cells than out = HYPOTONIC

28 Three examples of osmosis: 3
Three examples of osmosis: 3. More water moving out of cells than in = HYPERTONIC

29 Quick Question What should the solution in an IV bag be?
Equal amounts of water entering or exiting cells [Isotonic] More water entering cells [Hypotonic] More water leaving cells [Hypertonic]

30

31 Equilibrium When the concentration on both sides of the membrane is the same, it is called equilibrium.

32 WS 2-2 Cell Membrane Using your Text Book page 45 Complete Pages 4 & 5

33 Egg Lab Activity

34 Review Passive Movement across cell membrane
Osmosis – movement of water Diffusion – movement of everything else

35 Section Quiz

36 WS 2-2 Cell Membrane Review Do Pages 6 & 7 to


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