1. TRANSPORT IN CELLS

2. Cell Membrane Once believed to be a covering like a balloon.
“Gate keeper” allows materials in and out while maintaining the integrity of the cell.
Actually composed of many different molecules

3. Main structural component of cell membrane
Phospholipids
Main structural component of cell membrane

4. Proteins
Proteins embedded in membrane aid in the transport of large molecules and energy.

5. Carbohydrates
Function to help cells recognize other cells, hold proteins in place and provide energy for repair

6. Fluid Mosaic Model
All the molecules of the cell membrane are in constant motion. What benefit does the motion serve?

7. Cell Size is related to transport
Cell Size is related to transport. If the surface area to volume increases to much then materials will not be able to move in or out fast enough. A small cell is a more efficient cell.

8. PASSIVE TRANSPORT
MOVEMENT OF MOLECULES INTO OR OUT OF A CELL WITHOUT THE CELL USING ANY ENERGY MOLECULES MOVE DUE TO THEIR OWN KINETIC ENERGY… AS LONG AS THERE IS A CONCENTRATION GRADIENT PRESENT

9. DIFFUSION
Movement of any molecule from an area of greater concentration to an area of lesser concentration down a concentration gradient toward equilibrium.

10. Important Points… All states of matter can diffuse.
solids, liquids, gases
Diffusion can take place across a membrane
O2 and CO2 diffuse across cell membrane
Factors that affect rate of diffusion
Heat: warm materials diffuse faster
Motion: stirring or shaking increases diffusion
Surface area: greater surface area faster diffusion
Volume: smaller space faster diffusion

11. FACILITATED DIFFUSION
Transport of molecules across a membrane with the help of cell membrane proteins. Since the molecules are still moving down a concentration gradient no energy is required, so, it is still passive transport. WHAT MOLECULES NEED HELP? Polar molecules and ions are diffused across through channel proteins. They have charges and are repelled by the ends of the phospholipid molecules of the membrane Large molecules like amino acids and glucose are diffused across with the help of both channel and gated-channel proteins. Example: insulin ‘unlocks’ the gate to allow glucose into the cell

13. OSMOSIS
Very similar to diffusion with two exceptions: MOVEMENT OF WATER ACROSS A SEMI-PERMEABLE MEMBRANE From an area of greater concentration Down a concentration gradient Toward equilibrium

14. The direction the water moves, into or out of the cell… depends upon how much material, or, solute is dissolved in the water!

15. OK, here’s where it can get confusing!
Solutions are named based upon the amount of dissolved solute not the amount of water…
even though it’s the water that’s moving!

16. HYPERTONIC: HIGH SOLUTE CONCENTRATION outside cell membrane
LOW WATER CONCENTRATION
WATER MOVES OUT OF THE CELL
CAUSING IT TO SHRIVEL UP, THIS
IS CALLED PLASMOLYSIS

17. HYPOTONIC: LOW SOLUTE CONCENTRATION
outside cell membrane
HIGH WATER CONCENTRATION outside cell membrane
WATER MOVES INTO THE CELL
CAUSING IT TO SWELL, THIS IS
CALLED CYTOLYSIS, IF THE
WATER CANNOT BE
CONTROLLED THE CELL WILL
RUPTURE.

18. ISOTONIC: SOLUTE CONCENTRATION IS EQUAL TO WATER CONCENTRATION INSIDE AND OUTSIDE OF CELL WATER MOVES INTO AND OUT OF CELL EQUALLY, NET VOLUME IS MAINTAINED= HOMEOSTASIS

20. OSMOSIS PRACTICE Environment= 75% water Environment= 30% solute
Cell = 25% water Cell = 30% solute
Water moves__________ Water moves__________
Environment= 40% solute Environment is 10% water
Cell = 60% solute Cell = 90% water

21. I INITIAL OBSERVATION H
PRELAB QUESTIONS
What does the dialysis tubing represent?
What is an indicator?
For what substance is Lugol’s solution used as an indicator?
How does Lugol’s indicate its presence?
7. How does the test strip indicate the presence of glucose?
8. Why were you asked to test starch with a test strip?
A semi-permeable cell membrane
A chemical that tests for the presence of another, usually with a color change
Starch
Turns dark blue/black
Turns from teal to brown
As a control. Starch is made of
glucose monomers. There can be no ‘free’ glucose in the starch.
I INITIAL OBSERVATION H
FINAL OBSERVATION
BEAKER
STARCH
GLUCOSE
IODINE
MEMBRANE

22. I INITIAL OBSERVATION H
Homeostasis in Cells
I INITIAL OBSERVATION H
FINAL OBSERVATION
BEAKER
STARCH NO
GLUCOSE
IODINE
YES
MEMBRANE NO
YES
YES
YES
UNKNOWN
YES
GLUCOSE
STARCH
HYPOTONIC
HYPERTONIC
STARCH
GLUCOSE
WATER
STARCH
GLUCOSE
IODINE
WATER
DID NOT MOVE
TOO LARGE
IODINE
WATER
OUT OF MEMBRANE
DIFFUSION
INTO MEMBRANE
DIFFUSION
INTO MEMBRANE
OSMOSIS

24. I INITIAL OBSERVATION H
Homeostasis in Cells
I INITIAL OBSERVATION H
FINAL OBSERVATION
BEAKER
STARCH
GLUCOSE
IODINE
MEMBRANE

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