Warm Up 12/06/2018. In a Solution of Salt Water, which substance acts as the Solvent and which substance acts as the Solute?

Transcription

1 Warm Up 12/06/2018 In a Solution of Salt Water, which substance acts as the Solvent and which substance acts as the Solute?

2 Cell Membrane and Cell Transport How Nutrients move in and Wastes Move Out of the Cell

3 What is the Cell Membrane? The Cell Membrane is a complex structure that surrounds the Cell and regulates what enters and leaves the Cell.

4 What is the Cell Membrane Made of? The Cell Membrane is called a "Fluid Mosaic" because it is composed of many different types of Molecules. The most numerous molecule in the membrane are called Phospholipids.

5 What Are the Properties of the Cell Membrane? Today we will use bubbles to model the Cell Membrane. It is important to remember that the bubble is NOT the actual membrane, but it is a model that will allow us to see many of the membrane's properties. REMEMBER: All models have limits because they are representing the real thing!

6 Got a Cool Pic or Video? it: bryan.boulden@sussexvt.k12.de.us

7 We have learned: The Cell Membrane Cell Membranes are not static, they bend and flex in order to adapt to changing conditions Attraction between phospholipids allows cell membranes to repair small breaks in the bilayer The membranes surrounding organelles in Eukaryotic cells feature a phospholipid bilayer like the one found int he outer "plasma" membrane Some specialized proteins embed within the lipid bilayer, giving the membrane unique properties. Channel proteins are one example. They form a passage way for large or electrically charged molecules to pass through the membrane Gap junctions form between neighboring animal cells, allow their cytoplasm to connect directly. This provides a quick way for material to move between two cells. Some single-celled bacteria reproduce by splitting in two. This is known as binary fission.

8 Simple Diffusion The natural movement of molecules from areas of high concentration to areas of low concentration caused by their random motion. (NO ADDITIONAL ENERGY IS REQUIRED)

9 Passive Transport -When Molecules diffuse across the Cell Membrane due only to their random motion it is called Passive Transport -The key to identifying passive transport is that it is a type of transport that requires zero energy from the cell to perform -Water flows freely across the Cell membrane in a type of Passive Transport called Osmosis

10 Reaching Equilibrium -Passive Transport continues until there is an equal concentration of molecules on both sides of the Membrane -Molecules may still pass across the membrane after Equilibrium is reached, but the "net diffusion" has stopped.

11 Facilitated or "Helped" Passive Transport Some passive transport requires the help of a special helper channel or transmembrane protein. This still does not require energy

12 Vocabulary Solvent: The substance that has dissolved the solute. In living systems it is always water Solute: The substance that is in solution with the solvent. So for salt water: Water is the solvent Salt is the solute

13 Applying Vocabulary -In this example there are 2 Solutes (Purple and Orange Molecules) that are able to passively transport across the membrane -The Solutes diffuse across the membrane due to their own random motion until there is an equal concentration on each side of the membrane

14 Getting it Right with Salt The cell is always trying to maintain a concentration of salts that is equal to its watery environment. Cells can be found in 3 different types of watery environments: Isotonic: The concentration of salts and water are equal inside and outside of the Cell Hypertonic: The concentration of salts is greater outside of the cell Hypotonic: The concentration of salts is greater inside the Cell

15 How Does The Cell Respond to Different Environments

16 What Does Selectively Permeable Mean? In today's activity you will use Dialysis tubing to represent the cell membrane. You will setup an experiment to test the question: Can both Starch and Iodine pass through the Dialysis tubing Membrane?

17 What Does Our Experiment Need to Include? A Hypothesis A Control A Data Table Summary of Results/Tentative Conclusion

18 Starch A Large molecule that acts as a storage molecule for smaller Glucose molecules in plants.

19 Iodine Iodine is chemical element 53 on the Periodic Table Non-Metal 53 Protons, 53 Electrons 7 Valence Eectrons 5 Energy Shells

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21 Results... Iodine is able to diffuse through the membrane into the starch The Starch is unable to diffuse out of the membrane into the Iodine Like the Cell Membrane, the Dialysis tubing is Selectively Permeable

22 Warm Up 12/10/2018 Explain why Inside the "cell" turned purple but the cell's Iodine environment in the beaker did not.

23 What is an Egg?