Lab 5: Diffusion and Osmosis

The ______________ regulates what enters and leaves the cell

Plasma membrane

The plasma membrane is _______________________

Selectively permeable (chooses what goes in and out)

Diffusion is ____________________

The spread of particles through random motion from regions of high concentration to regions of low concentration

Osmosis is __________________

The diffusion of water through a selectively permeable membrane

Passive processes _______________ energy for movement of molecules

Passive processes DO NOT REQUIRE energy for movement of molecules

Active processes ___________ energy for movement of molecules

Active processes REQUIRE energy for movement of molecule

The concentration of solute describes ________________

How much solute is in it

Solute is _____________________

The dissolved substance in a solution

Solvent is _________________________

The dissolving substance n a solution

An example of solute and solvent is ________________

Solution = salt water

Solute = salt

Solvent = water

Solute = dissolvED

Solvent = dissolvING

Concentration gradient is _______________

Te difference in solute concentration across the plasma membrane

Deionized water (DI) is ______________________

Water that had all the charged ions removed (aka PURE water)

PROCEDURE ONE: Diffusion, dye through agar gel. What are you doing?

Comparing the rate of diffusion through a semi-solid (agar) and water, using potassium permanganate (MW=158) and methylene blue (MW=320)

What is the result of procedure one, where diffusion of dye (potassium permanganate and methylene blue) through agar gel, take place?

Potassium permanganate diffused faster/the farthest because it weight significantly less than methylene blue, making it easier for it to travel faster and farther.

PROCEDURE TWO: Diffusion, across a plasma membrane. What are you doing?

A selectively permeable membrane is used to show diffusion. A dialysis tubing (which contains pores that regulates which molecules go through depending on size). Inside the tubing, glucose and starch is inserted. The tubing is then placed in a beaker filled with water and iodine. The iodine will help show the presence of starch.

What is the result of procedure two: diffusion, across a plasma membrane?

The glucose within the tube will diffuse across the membrane from a region of high concentration to a region of low concentration. It is able to diffuse through the membrane because it is smaller than the starch. The results are visible because the iodine caused the solution in the dialysis tubing to turn dark blue/black, showing that the starch is present in the tubing. The solution outside remained gold/brown, meaning iodine was negative. The dialysis bag also weighed less, proving that the glucose did in fact diffuse across the membrane.

PROCEDURE THREE: Osomosis, in a potato (plant) cell. What do you do?

Two pieces of potatoes bored out. Measure out each piece to be the same length and place one in a 10% salt solution and in DI water. Calculate the change of mass using the formula: Final mass (g) - initial mass

What are the results of procedure three: osmosis, in a potato (plant) cell?

The potato in the DI water has the same weight aka isotonic. Since DI water has no solutes and water chases solutes, the cell remained the same. The potato in the 10% solution, however, decreased in mass because the salt solute drew out water from the potato, thus reducing the size of the potato. (aka hypertonic)

What happens to plant cells in:

- Hypertonic solution

- Isotonic solution

- Hypotonic solution

- Hypertonic --> Plasmolyzed (water goes out and inside shrivels)

- Isotonic --> Normal shape (water goes in and out and stays the same)

- Hypotonic --> Cell is turgid (water goes in and cell swells, but does not lyse)

What happens to animal cells in:

- Hypertonic solution

- Isotonic solution

- Hypotonic solution

- Hypertonic --> shrivels

- Isotonic --> normal shape

- Hypotonic --> cell swells and may lyse

What is crenation?

When RBC in hypertonic solution shrink and appears shriveled/dehydrated

What is hemolysis?

When RBC in hypotonic solutions burst and spill their contents into the surrounding fluid

Animal cells in:

- 5% Salt Solution

- 0.9% saline solution

- DI water

- 5% salt sol --> hypertonic (cell shrinks and may undergo crenation)

- 0.9% saline solution -- > isotonic (cell stays the same bc 0.9% saline sol is the closest to the actual solute concentration of blood)

- DI water --> hypotonic (cell swells and may undergo hydrolysis and burst)

**water chases solutes

Plant cells in:

- 10% salt sol

- tap water

- DI water

- 10% salt sol --> hypertonic (plasmolyzed)

- tap water --> isotonic (normal bc has some water, has some solutes, will disperse equally)

- DI water --> hypotonic (turgid bc DI water has no solutes, it is pure water, and water chases solutes therefore going into the cell)