* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Cell_Transport_2014
Survey
Document related concepts
Lipid bilayer wikipedia , lookup
Biochemical switches in the cell cycle wikipedia , lookup
Membrane potential wikipedia , lookup
Cell nucleus wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell growth wikipedia , lookup
Signal transduction wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
Cellular Transport Notes Ch. 7.4 About Cell Membranes 1. All cells have a cell membrane 2. Functions: a. Controls what enters and exits the cell to maintain an internal balance called homeostasis. b. Provides protection and support for the cell. TEM picture of a real cell membrane. About Cell Membranes (Continued) 3. Structure of cell membrane: Phosphlipid Bilayer - 2 layers of phospholipids a. Phosphate head is polar (water loving) b. Fatty acid tails non-polar (water fearing) c. Proteins embedded in membrane Phospholipid Lipid Bilayer Polar heads love water. Fluid Mosaic Model of the cell membrane Non-polar tails hide from water. Carbohydrate cell markers Proteins Membrane movement animation About Cell Membranes (continued) • 4. Cell membrane has pores (holes) in it. a. Selectively Permeable - allows some molecules in and keeps other molecules out. b. The structure helps it to be selective! Pores Structure of the Cell Membrane Outside of cell Proteins Lipid Bilayer Transport Protein Animations of membrane Go to structure Section: Carbohydrate chains Phospholipids Inside of cell (cytoplasm) Cells… • Have to maintain a constant internal environment (or homeostasis) • respond to the concentration gradient of the environment by moving molecules across membranes to balance inside and outside concentrations (i.e. equilibrium) or to stockpile more. Transport Begins with Tonicity Tonicity is the concentration of dissolved solutes inside compared to outside the cell. 1. Determine the concentration of solutes found inside the cell 2. Determine the concentration of solutes found outside the cell 3. Compare the two – where is the concentration greater? 4. Molecules move from high to low! Isotonic • Concentration of dissolved solutes outside the cell is equal to concentration of the cell’s contents. Hypertonic • Hyper = there is a higher solute concentration outside the cell. This will draw water out of cell causing cell to shrivel. Hypotonic • Hypo = there is a low solute concentration outside the cell as compared to inside the cell. This will cause cell to swell as water moves in. • So once we know the concentration gradient we can start thinking about how cells move molecules in and out of the cell… Types of Cellular Transport • Weeee!! ! Passive Transport cell doesn’t need to use energy 1. Diffusion (simple) 2. Facilitated Diffusion 3. Osmosis • •Animations of Active Transport & Passive Transport high low Active Transport cell needs to use energy 1. ION Pumps 2. Endocytosis 3. Exocytosis This is gonna be hard work!! high low • OSMOSIS by The AMOEBA SISTERS: • http://www.youtube.com/watch?v=EmJFgk cbzVg&list=UUb2GCoLSBXjmI_Qj1vk-44g Passive Transport Active Transport • No energy required • Movement from high to low area of concentration • Molecules move with concentration gradient • Diffusion • Osmosis • Facilitated diffusion • Requires energy. • Movement from low to high area of concentration. • Molecules move against the concentration gradient. • Sodium-potassium ion pump. • Endocytosis • Exocytosis Passive Transport: 1. Diffusion Simple Diffusion Animation 1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration. (High to Low) • Diffusion continues until all molecules are evenly spaced (equilibrium is reached) - Note: molecules will still move around but stay spread out. http://bio.winona.edu/berg/Free.htm Types of Passive Transport (high to low) 1. Diffusion • Molecules move from an area of high concentration to an area of low concentration Click here for diffusion animated explanation Passive Transport (continued) 2. Facilitated Diffusion: diffusion of specific particles through transport proteins found in the membrane a.Transport Proteins are specific – they “select” only certain molecules to cross the membrane b.Transports larger or charged molecules A B Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Carrier Protein Types of Passive Transport (high to low) Facilitated Diffusion • Diffusion of bigger molecules (but still smaller than particles) through channel proteins Click here for facilitated diffusion explanation Passive Transport: 2. Facilitated Diffusion Glucose molecules Cellular Transport From aHigh Concentration High • Channel Proteins animations Cell Membrane Low Concentration Through a Go to Section: Transport Protein Protein channel Low Passive Transport: 3. Osmosis Osmosis animation • 3. Osmosis: diffusion of water through a selectively permeable membrane. • Water moves from high to low concentrations. •Water moves freely through pores. •Solute (green) to large to move across. Passive Transport Active Transport • No energy required • Movement from high to low area of concentration • Molecules move with concentration gradient • Diffusion • Osmosis • Facilitated diffusion • Requires energy • Movement from low to high area of concentration • Molecules move against concentration gradient • Sodium-potassium ion pump • Endocytosis • Exocytosis Types of Active Transport 1. Protein Pumps transport proteins that require energy to do work •Example: Sodium / Potassium Pumps are important in nerve responses. Sodium Potassium Pumps (Active Transport using proteins) Protein changes shape to move molecules: this requires energy! Types of Active Transport (low to high) Ion pump Ions are stockpiled in an already highly concentrated area Click here for Sodium-potassium pump animation Types of Active Transport • 2. Endocytosis: taking bulky material into a cell • Uses energy • Cell membrane in-folds around food particle • “cell eating” • Think pac-man • This is how white blood cells eat bacteria! Types of Active Transport 3. Exocytosis: Forces material out of cell in bulk cell “pooping” • membrane surrounding the material fuses with cell membrane • Cell changes shape – requires energy Endocytosis & Exocytosis animations Endocytosis (in) & Exocytosis (out) Summary Passive Transport • No energy required • Movement with the concentration gradient • Diffusion, osmosis, facilitated diffusion • Maintains equilibrium Both Active Transport • Movement through channel proteins • Requires ATP • Movement of small ions & molecules • Ion pump or endo/exocytosis • Maintains homeostasis • Movement against gradient • Movement of large particles • Stockpiles materials (extra’s) NOW WE’LL FOCUS ON WATER MOVEMENT BECAUSE IT MOVES MORE FREELY THAN OTHER MOLECULES Notice the sugar molecules are too big to pass through the membrane but water is not Effects of Osmosis on Life • Osmosis- diffusion of water through a selectively permeable membrane Next lets see how different conditions (iso/hypo/hyper) can affect a cell by osmosis … • Hypotonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)! Hypotonic solution • Water moves inside of cell, toward higher solute concentration • Cell size increases * Note the cell is hypertonic compared to the solution around it How will you remember? Think hypo-hippo A cell in a hypo- environment will swell like a big fat hippo! • Hypertonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)! Hypertonic solution • Water moves outside of the cell, toward higher solute concentration • Cell size shrinks * Note the cell is hypotonic compared to the solution around it • Isotonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) Isotonic solution • Water moves equally in BOTH directions • Therefore, cell size does not change * Note the cell is also isotonic compared to the solution around it What type of solution are these cells in? A B C Hypertonic Isotonic Hypotonic Review • • • • Hypotonic Lower solute concentration outside the cell Water moves in Cell size increases E.g. Diluted solution Isotonic • Same solute concentration • Water moves in and out • No change in cell size • • • • Hypertonic Higher solute concentration outside the cell Water moves out Cell size decreases E.g. Strong salt solution