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Benchmark & Essential Question
SC.912.L.14.2: Relate structure to function for the components of plant and animal cells. Explain the role of cell membranes as a highly selective barrier Essential Question: How do materials enter and exit the cell?
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How Does The Game Red Rover Represent the Cell Membrane? (Video)
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DAY 1: The Cell Membrane Look at the image to the right.
By the end of todays lesson: You will be able to describe the structure of the cell membrane and explain how it contributes to its function. Look at the image to the right. What’s happening? Cell membrane
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Before we begin let’s see what the Amoeba Sisters have to say about Homeostasis & The Cell Membrane!!! Video
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TEM picture of a real cell membrane.
REMEMBER: All cells have a cell membrane Functions: Controls what enters and exits the cell to maintain an internal balance called homeostasis Provides protection and support for the cell TEM picture of a real cell membrane.
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Structure of Cell Membrane
Phospholipid Bilayer -2 layers of phospholipids Phosphate head is polar (hydrophilic=water loving) Fatty acid tails are non-polar (hydrophobic=water fearing) Proteins embedded in membrane Phosphate head Fatty Acid Tails Phospholipid Bilayer
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Non-polar tails hide from water. More macromolecules in
Polar heads love water & dissolve. Fluid Mosaic Model of The Cell Membrane Non-polar tails hide from water. More macromolecules in the cell membrane!!! Carbohydrate cell markers Proteins
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CELL MEMBRANE “FLUID MOSAIC” “ID tags” “transport” “Phospholipids”
Outside of cell Inside (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains CELL MEMBRANE “FLUID MOSAIC” “ID tags” “transport” “Phospholipids”
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SELECTIVELY PERMEABLE
Cell membranes control what gets in or out of the cell. It needs to allow some materials but not all to pass through the membrane It is Selectively Permeable: Allows some molecules in and keeping other molecules out. The structure helps it be selective.
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CELL MEMBRANE CHANNELS
Need to make “doors” through membrane PROTEIN CHANNELS:allow substances in & out specific channels allow specific material in & out H2O channel, salt channel, sugar channel, etc. inside cell aa sugar waste outside cell
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protein channels in bi-lipid membrane
Proteins Channels like water and lipids! Look at the last picture. How is the protein both hydrophobic and hydrophilic? bi-lipid membrane protein channels in bi-lipid membrane
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Check For Understanding # 3
In this fluid mosaic model of the cell membrane, why are the lipid tails facing the inside of the membrane and the phosphate heads face towards the outside of the cell?
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DAY 2: PASSIVE TRANSPORTS
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Types of Cellular Transport
PASSIVE TRANSPORT Cell DOES NOT use energy Molecules move randomly from high concentration to low concentration. Types of Passive Transport Diffusion Facilitated Diffusion Osmosis high low Weeee!!!
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AIR FRESHNER DEMO “Who Smells It First?”
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Passive Transport (Continued) DIFFUSION
Diffusion: random movement of particles directly across the cell membrane from an area of high concentration to an area of low concentration. A concentration gradient is the difference in the concentration of a substance from one location to another. (High to Low) Diffusion continues until all are molecules evenly spaced (equilibrium is reached)- Note: molecules will still move around but stay spread out. Simple Diffusion Animation
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Passive Transport FACILITATED DIFFUSION
Facilitated Diffusion: random movement of particles across the cell membrane through a protein channel from an area of high concentration to an area of low concentration. No ATP required! Simple diffusion Facilitated diffusion
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Passive Transport (Continued) OSMOSIS
Osmosis: diffusion of water through a selectively permeable membrane Water moves from high to low concentrations Water moves freely through pores. Solute (green) too large to move across. Let’s see what Amoeba Sisters have to say on the subject!
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Types of Osmotic Solutions
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Cells in a hypertonic solution
In a hypertonic solution, there is a high concentration of solutes outside of the cell. Water leaves a cell by osmosis, causing the cell to shrink. H2O 1 H2O shrink Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!
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Cells in a hypotonic solution “Hypo”= hippo=swollen
In a hypotonic solution, there’s a high concentration of solutes inside of the cell. Water enters a cell by osmosis, causing the cell to swell. “Hypo”= hippo=swollen H2O H2O Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!
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Check For Understanding:
Explain why is this gummy bear sitting in the cup of water is swollen?
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Cells in an isotonic solution
In an isotonic solution, the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside the cell. H2O H2O Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)
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Check For Understanding: What type of solution are these cells in?
Hypertonic Isotonic Hypotonic
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DAY 4: ACTIVE TRANSPORT
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Types of Cellular Transport
ACTIVE TRANSPORT Cell DOES use energy Actively move molecules to where they’re needed from low to high concentration These molecules move against the concentration gradient. They require protein pumps and ATP. 1.) Protein Pumps 2.) Endocytosis 3.) Exocytosis high low This is going to be hard work!!
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Transport Summary
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Protein changes shape to move molecules: this requires energy!
Proteins Pumps Proteins do much of the work in active transport. Protein Pumps –change shape to transport proteins that require energy to do work Example: Sodium / Potassium Pumps are important in nerve responses. Protein changes shape to move molecules: this requires energy!
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Active Transport ENDOCYTOSIS: is a process by which a cell surrounds and takes in material from its environment. Uses energy Cell membrane in-folds around food particle “cell eating”(phagocytosis) forms food vacuole & digests food This is how white blood cells eat bacteria!
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Section 8.1 Summary – pages 195 - 200
Transport of Large Particles ENDOCYTOSIS Nucleus Digestion Exocytosis Endocytosis Wastes removal Section 8.1 Summary – pages
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Active Transport EXOCYTOSIS: Forces material out of cell in bulk
membrane surrounding the material fuses with cell membrane Cell changes shape – requires energy EX: Hormones or wastes released from cell
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Section 8.1 Summary – pages 195 - 200
Transport of Large Particles EXOCYTOSIS Nucleus Digestion Exocytosis Endocytosis Wastes removal Section 8.1 Summary – pages
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Endocytosis vs. Exocytosis
Large molecules and clumps of material can be taken into the cell by a process known as ___________. The two kinds of endocytosis are: 1. Phagocytosis= 2. Pinocytosis= ___________= release of large amounts of material Endocytosis ‘Cell eating’ ‘cell drinking’ Exocytosis
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Osmosis (same as diffusion w/water)
Review interactive sites for cell membrane, diffusion, active, passive transport PASSIVE TRANSPORT ACTIVE TRANSPORT Diffusion Osmosis (same as diffusion w/water) Endocytosis & Exocytosis No ATP No ATP ATP required High to Low High to Low Low to High No protein No Protein Needs Protein
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Strange But True Article Questions Directions: Answer The Following Questions after you’ve read the article: 1.) Describe what happened to the 28 year old California woman. 2.) What is hyponatremia? What can it lead to? 3.) What are symptoms of water intoxication? 4.) What is the function of the kidneys? 5.) How does drinking too much water in a short amount of time prevent the kidneys from functioning properly? 6.) What type of solution does the body become if there is too much water? (hypertonic, hypotonic, isotonic) 7.) What will happen to the cells in the body as a result? 8.) Give specific examples (i.e what happens to the brain?) 9.) What is water poisoning a combination of? 10.) How should you balance what you are drinking while exercising?
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