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Cellular Transport

Cellular Transport. Cell Membranes and Interaction with their environment. Cell Membranes. Structure and Functions. Cell Membranes. All cells have a cell membrane Functions : Controls what enters and exits the cell to maintain an internal balance called homeostasis

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Cellular Transport

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  1. Cellular Transport Cell Membranes and Interaction with their environment

  2. Cell Membranes Structure and Functions

  3. Cell Membranes • 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

  4. Cell Membranes • Structure of cell membrane Lipid Bilayer-2 layers of phospholipids • Phosphate head is polar(water loving) • Fatty acid tails non-polar(water fearing) • Proteins embedded in membrane Polar heads love water Non-polar tails hide from water. Proteins

  5. Cell Membranes • Cell membranes have pores (holes) in it • Selectively permeable (semi-permeable): Allows some molecules in and keeps other molecules out • Take cell membrane quiz! • http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP1101

  6. Cell Transport

  7. Types of Cell Transport • Passive Transport • Active Transport • Endocytosis • Exocytosis

  8. Passive Transport

  9. Passive Transport Characteristics Types of Passive Transport • No energy required • Move due to gradient • differences in concentration, pressure, charge • Move to equalize gradient • HIGH  low 1. Diffusion 2. Facilitated diffusion 3. Osmosis

  10. Vocab • Concentration gradient is the different amounts of solutes or substances in one place • Solute – a SUBSTANCE dissolved in a fluid • Solvent – the FLUID part of a solution • Solution – a MIXTURE of two or more substances (a solute and solvent)

  11. Diffusion • Diffusionis the movement of any particles from an area of HIGH concentration to an area of low concentration. • Molecules move to equalize concentration

  12. Equilibrium • Equilibrium– occurs when the particles that were diffusing are now equally distributed

  13. Movement Across the Cell Membrane • A few molecules diffuse freely across the membrane: • Water, • Carbon dioxide, • Ammonia, • Oxygen

  14. Facilitated Diffusion 2. Facilitated Diffusion is diffusion of specific particles through transport proteinsfound in the membrane • Channels (are specific) help molecule or ions enter or leave the cell • No energy is used

  15. Process of Facilitated Transport • Protein binds with molecule • Shape of protein changes • Molecule moves across membrane

  16. Osmosis • Osmosis- diffusion of water through a selectively permeable membrane • Water is so small and there is so much of it the cell can’t control its movement through the cell membrane. • Equilibriumoccurs until water is balanced on both sides of the membrane. • ONLY WATER DIFFUSES IN OSMOSIS!!!

  17. Solute/Solvent/Solution • This is sugar water. • What is the solute? • What is the solvent? • What is the whole mixture called?

  18. Solute/Solvent/Solution • A glass of iced tea. • What is the solute? • What is the solvent? • What is the whole mixture called?

  19. Solute/Solvent/Solution • Ex: Propel Energy Drink • What is the solute? • What is the solvent? • What is the whole mixture called?

  20. Solute/Solvent/Solution • Ex: Dr. Pepper • What is the solute(s)? • What is the solvent? • What is the whole mixture called?

  21. Osmosis • What direction will the water go? • are solutes

  22. Types of Osmosis: • Hypertonic solutions – more dissolved solutes • Hypotonic solutions – less dissolved solutes • Isotonic solutions – the same dissolved solutes “Hyper-” means over, above, a lot “Hypo-” means under, below “Iso-” means equal or the same

  23. Hypertonic Solution • More soluteoutside the cell • Less water outside the cell Result: The WATER will move OUT of the cell, causing the cell to shrink (or crenate) Osmosis Animations for isotonic, hypertonic, and hypotonic solutions

  24. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic Solution • Less soluteoutside of the cell • More wateroutside of the cell Result: The WATER will move INTO the cell, causing the cell to swell or burst (lysis)

  25. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic Solution • Wateris the same outside the cell and the same inside the cell. • Solutesare the same inside the cell as outside the cell. • Result: Wateris moving in and out at the same rate

  26. How Organisms Deal with Osmotic Pressure • Paramecium (protist) removing excess water video • Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure. • A protist like paramecium have contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. • Salt water fish pump salt out of their specialized gillsso they do not dehydrate. • Animal cells are bathed in blood. Kidneyskeep the blood isotonic by removing excess salt and water.

  27. Inquiry Osmosis Egg Lab A study of Tonicity in Cells

  28. Active Transport

  29. Active Transport Characteristics Types of Active Transport • Molecular movement requires energy/ATP to move against the concentration gradient • LOW  high • Example is sodium-potassium pump • Endocytosis • Exocytosis

  30. Endocytosis • Movement of large material • Particles • Organisms • Large molecules • Movement is into cells • Types of endocytosis • bulk-phase (nonspecific) • receptor-mediated (specific)

  31. Process of Endocytosis • Plasma membrane surrounds material • Edges of membrane meet • Membranes fuse to form vesicle

  32. Forms of Endocytosis • Phagocytosis – cell eating • Pinocytosis – cell drinking

  33. Exocytosis • Reverse of endocytosis • Cell moves material OUTSIDE the cell

  34. Exocytosis • Vesicle moves to cell surface • Membrane of vesicle fuses • Materials expelled

  35. Active Transport • cell usesenergy (in the form of ATP) • actively moves molecules to where they are needed • Movement from an area of low concentration to an area of high concentration • (Low  High) • Three Types

  36. Types of Active Transport • 1. Protein Pumps-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!

  37. Types of Active Transport • 2.Endocytosis: taking bulky material into a cell • Uses energy • Cell membrane folds in around food particle creating a vesicle that is made of the cell membrane • “cell eating” • Lysosomes come and digests food • This is how white blood cells eat bacteria!

  38. Types of Active Transport 3. Exocytosis:Forces material out of cellin 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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