Transcript Inside Cell
Moving through the Plasma Membrane What does a phospholipid look like? Let’s Review • What is homeostasis? • What is the job of the plasma membrane? • How do you think the cell membrane helps a cell maintain homeostasis? What does the Plasma Membrane look like? Outside Cell (Extracellular Matrix) Protein Glycoprotein Cholesterol Inside Cell (Cytoplasm) Phospholipids The Plasma Membrane Outside Cell (Extracellular Matrix) Protein Glycoprotein Cholesterol Phospholipids Inside Cell (Cytoplasm) The Plasma Membrane Polar Non-Polar Outside Cell (Extracellular Matrix) Protein Glycoprotein Phospholipids Cholesterol Inside Cell (Cytoplasm) Plasma Membrane: The Fluid Mosaic Model Plasma Membrane: The Fluid Mosaic Model • Fluid because –the phospholipid and protein molecules are able to move around. Not stuck in one place. • Mosaic because – the membrane contains a variety of proteins embedded with the phospholipids. How do particles move in and out of the cell? Passive Transport energy • No additional _______________ is required because every particle has its own energy • This energy produces random ________________ movement in particles. (a.k.a Brownian motion) Diffusion • Diffusion is the movement of high substances from a ________ concentration to a low concentration. amount • Concentration is the _________ area of something in a given ______. How does it work? • Particles move down the concentration gradient, until equal the concentration is _________ throughout an area. • Then the system is said to have reached dynamic equilibrium. A. High Concentration of Blue Dots High Concentration of Orange Dots Low Concentration of Orange Dots Low Concentration of Blue Dots B. System has reached dynamic equilibrium Examples of diffusion at work • Why does food smell fragrant when cooked? • Have you ever stood next to someone wearing strong perfume? Permeability of a membrane • Permeable: anything can pass through • Semi-permeable: some things can pass through • Impermeable: nothing can pass through Back to the plasma membrane… Outside Cell (Extracellular Matrix) Inside Cell (Cytoplasm) • The plasma membrane is described as semi-permeable because some substances can move through it: –Small and –Non-polar Osmosis • Diffusion of _________ water across a membrane • Water molecules can pass through pores or openings proteins in the created by __________ plasma membrane . Back to the plasma membrane… Outside Cell (Extracellular Matrix) Protein Glycoprotein Cholesterol Inside Cell (Cytoplasm) Phospholipids The Cell’s Environment: Isotonic • In an isotonic environment the solute concentrations are equal ___________ and there is no NET movement of water. The Cell’s Environment: Hypotonic • In a hypotonic environment, there are less __________ solutes outside than inside and water moves into the cell. The Cell’s Environment: Hypertonic • In a hypertonic environment there are more solutes outside _________ than inside and water moves out of the cell. Environment Water Effect on Effect on outside cell moves… ANIMAL cell PLANT cell Hypotonic Hypertonic Isotonic Environment Water Effect on Effect on outside cell moves… ANIMAL cell PLANT cell Hypotonic Hypertonic Isotonic In Swells, then bursts (cytolysis) Animal Cell Cytolysis Cells burst Cell still intact Environment Water Effect on Effect on outside cell moves… ANIMAL cell PLANT cell Hypotonic Hypertonic Isotonic In Swells, Swells, then bursts increases (cytolysis) turgor pressure Environment Water Effect on Effect on outside cell moves… ANIMAL cell PLANT cell Hypotonic In Hypertonic Out Isotonic Swells, Swells, then bursts increases (cytolysis) turgor pressure Environment Water Effect on Effect on outside cell moves… ANIMAL cell PLANT cell Hypotonic In Swells, Swells, then bursts increases (cytolysis) turgor pressure Hypertonic out Shrinks (crenation) Isotonic Environment Water Effect on outside cell moves… ANIMAL cell Hypotonic In Swells, Effect on PLANT cell Hypertonic Shrink (plasmolysis) Swells, then bursts increases (cytolysis) turgor pressure Isotonic out Shrinks (crenation) Environment outside cell Water moves… Effect on Effect on ANIMAL cell PLANT cell Hypotonic In Hypertonic Out Swells, then Swells, bursts increased (cytolysis) turgor pressure Shrinks Shrinks, (crenation) (plasmolysis) Isotonic Environment Water Effect on outside cell moves… ANIMAL cell Hypotonic In Swells, Effect on PLANT cell Hypertonic Shrink (plasmolysis) Swells, then bursts increases (cytolysis) turgor pressure Isotonic out Shrinks (crenation) Plant cell: Plasmolysis Plasmolyzed Cells Normal cells Environment Water Effect on outside cell moves… ANIMAL cell Hypotonic In Swells, Effect on PLANT cell Hypertonic out Shrink (plasmolysis) Isotonic In and out at the same rate Swells, then bursts increases (cytolysis) turgor pressure Shrinks (crenation) Environment Water Effect on outside cell moves… ANIMAL cell Hypotonic In Swells, Effect on PLANT cell Hypertonic out Shrink (plasmolysis) Isotonic In and Stays the out at same the same rate Swells, then bursts increases (cytolysis) turgor pressure Shrinks (crenation) Environment Water Effect on outside cell moves… ANIMAL cell Hypotonic In Swells, Effect on PLANT cell Hypertonic out Shrink (plasmolysis) Isotonic In and Stays the out at same the same rate Swells, then bursts increases (cytolysis) turgor pressure Shrinks (crenation) Stays the same Osmosis in Action • What happens when you sprinkle salt on a slug? • If you are stranded at sea and run out of water, should you drink sea water? ** Water moves from a hypo to a hypertonic environment. True or False 1. In diffusion, particles move from an area of high to low concentration. 2. Diffusion does not require any additional energy to occur. 3. Small, charged or polar particles can move through the cell membrane by simple diffusion. What if a cell needs large or charged/ polar molecules. Can they move across the membrane? Yes! Selectively Permeable Membrane • Proteins in the membrane allow specific macromolecules or ions in or out of the cell. Facilitated diffusion • Proteins help particles move across the membrane • Transport proteins span the phospholipid bilayer, but specific allow only ___________ molecules through. >> Selectivity Types of transport proteins Ion channels • ____ __________ are non–polar on the outside and polar on the inside. They provide a pore for ions and polar particles to move through. Carrier Proteins • _________ _______________ bind to specific particles, carry them through the membrane, and release them on the other side. http://www.stolaf.edu/people/giannini/flashanimat/transport/caryprot.swf Remember! • In diffusion-particles (solutes) move from an area of HIGH concentration to LOW • In osmosis- water moves from a HYPOTONIC environment to a HYPERTONIC environment • Diffusion requires NO energy input • http://scienceguyinatie.blogspot.com/2008/11/cell-membrane-animation-of-word-wall.html Simple vs. Facilitated • In simple diffusion, particles move between phospholipid molecules of the membrane. • In facilitated diffusion, particles move through transport proteins in the membrane. • Both do NOT use energy. Particles must move down the concentration gradient. What if you needed to move particles against their concentration gradient? Active Transport • Transport proteins use energy to move particles against their concentration gradient (low high). Sodium-Potassium Pump: • Carrier- protein that pumps 3 sodium ions (Na+)outside the cell, while pumping 2 potassium ions (K+)inside. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html 1. 3 Na+ ions bind to the pump protein inside. ATP adds energy to the pump. 2. The pump moves the Na+ ions outside of the cell. 3. 3 Na+ ions are released and 2 K+ ions bind to the pump. 4. The pump moves the 2 K+ ions inside the cell. Vesicle Mediated Transport • The fluid plasma membrane can “pinch” off forming vesicles that can move very large particles or lots of small particles. • This process needs energy. Endocytosis • Outside materials are brought inside the cell. 1) Food particle 2) Pouch forming around food 3) Vesicle with food Endocytosis Phagocytosis • “Cell eating” • Cell engulfs large food particles and the vesicle is a food vacuole. • http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/phagocitosis.swf Pinocytosis • “cell drinking” • Cell engulfs small droplets of surrounding fluid. Exocytosis • Material from inside the cell is released outside by vesicles. 1) Vesicle fuses with membrane 2) Pouch opens 3) Particle released Your turn! Create a graphic organizer that compares: • Simple diffusion • Facilitated diffusion –Ion channel –Carrier proteins • Active Transport –Protein Pumps –Vesicle Mediated Transport