1 of 27

Diffusion & Osmosis

Accelerated Biology

2015

2 of 27

2

1.) What are 2 main molecular constituents of a

cell membrane?

-Phospholipid Bilayer, Proteins

3 of 27

3

What are 4 different types of proteins

in a cell membrane?

-Transport, Recognition, Adhesion, Receptor

4 of 27

a. Transport protein

c. Recognition protein

d. Receptor protein

b. Adhesion protein

5 of 27

5

​

3.) The Fluid Mosaic membrane is our current concept of the cell membrane.

a) Explain the term mosaic with respect to membranes.

b) Why is a membrane considered fluid?

6 of 27

6

What type of molecules can’t get through a

membrane? (hint: they rhyme)

LARGE AND CHARGED

7 of 27

7

Observe: What do you notice happening to the food coloring?

Question: What do you think will happen when we drop food coloring into the cup of water?

​

Explain: What is happening?

PREDICT: Draw a picture and/or explain why.

8 of 27

Diffusion

9 of 27

Diffusion

  • Solutes (or molecules) are moving
  • Moves from an area of high concentration to an area of low concentration ( HIGH → low )
  • Moves until it is equal everywhere (until it “reaches an equilibrium”)

10 of 27

Osmosis

11 of 27

Osmosis

  • Water is moving
  • Must have a semi-permeable membrane
  • Water moves because the solute can’t
  • Water moves toward where there is more solute (tries to dilute the solute to reach an equilibrium)

12 of 27

Solutions

  • Isotonic solutions – same tonicity
  • Hypotonic solutions – lower solute content than inside a cell
  • Hypertonic solutions – higher solute content than inside a cell

13 of 27

Isotonic solution

14 of 27

Isotonic

15 of 27

Hypotonic Solution

16 of 27

Hypotonic

17 of 27

Hypertonic Solutions

18 of 27

Hypertonic

Crenated Red Blood Cells (RBC) Plasmolysis

19 of 27

Show Campbell video of paramecium

20 of 27

21 of 27

Exocytosis

22 of 27

23 of 27

24 of 27

Differences

Osmosis

Diffusion

  • Takes place with a semipermeable membrane
  • Molecules flow in one direction only
  • Slower in nature
  • Takes place over short distances only
  • Takes place only in water
  • Takes place w/o a membrane
  • Molecules flow in any direction
  • Has a faster rate
  • Takes place over short and long distances
  • Isn’t dependent in water

25 of 27

26 of 27

Hypothesis:

  • If an egg is put into a HYPOTONIC solution, what will happen to the egg? (will the size increase, decrease, or stay the same?)
  • If an egg is put into a HYPERTONIC solution, what will happen to the egg? (will the size increase, decrease, or stay the same?)

​

27 of 27

Egg Osmosis

What happened?

1.) What happened to the egg in the karo syrup?

Include:

  • Hypothesis
  • Picture of water molecules moving across the membrane.
  • Explanation why
  • Include terms:
    • Hypotonic, hypertonic, equilibrium, osmosis, diffusion

​

Mass Before: 98.2 g after: 52.8g