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Plasma Membrane

Plasma Membrane. Movement in and out of a cell. Plasma Membrane. A flexible boundary between the cell and it’s environment JOB: allow steady supply of nutrients to come into the cell no matter what the external conditions are Too much of any nutrient or other substance can be harmful.

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Plasma Membrane

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  1. Plasma Membrane Movement in and out of a cell

  2. Plasma Membrane • A flexible boundary between the cell and it’s environment • JOB: allow steady supply of nutrients to come into the cell no matter what the external conditions are • Too much of any nutrient or other substance can be harmful

  3. Plasma Membrane (PM) • Process of maintaining balance in a cell’s environment is homeostasis • Selective permeability allows some molecules to pass through while keeping other out • Ex: screen on a window

  4. PM: Structure • Lipids are large biomolecules composed of glycerol and 3 fatty acids • If a phosphate replaces one of the fatty acids, a phospholipid is formed • PM is made up of a phospholipid bilayer (2 layers of phospholipids back-to-back

  5. PM: Structure • 2 fatty acid chains are non-polar and form the tail of the phospholipid • The head contains the phosphate group and is polar

  6. Continued • Water is a key component of life • Polar head allows PM to interact with watery environment (H2O is a polar molecule) (Hydrophyllic) water loving • Non-polar tails avoid water (Hydrophobic) water fearing • Phospholipid molecules make a sandwich with tails in, heads out.

  7. PM: Fluid Mosaic Model • PM is not static (it doesn’t stay still) • Phospholipids move within the membrane like water molecules move with currents in a lake • Proteins also move through phospholipids like boats • Proteins create “mosaic” or pattern on membrane surface

  8. PM: Other Components • Cholesterol: helps stabilize phospholipids by preventing tails from sticking together • Transport proteins: Span entire membrane • Regulate which molecules enter and leave cell • Proteins on OUTER surface help cells identify chemical signals and each other • Proteins on INNER surface help attach PM to cells internal support structure  flexibility

  9. PM: Other Components

  10. Show me What You Know The structure most responsible for maintaining cell homeostasis is the ___. • Cytoplasm • Mitochondrion • Cell Wall • Plasma Membrane

  11. Show me What You Know The structure most responsible for maintaining cell homeostasis is the ___. • Cytoplasm • Mitochondrion • Cell Wall • Plasma Membrane

  12. Show Me What You Know Movement of particles from an area of higher concentration to one of lower concentration is ______________?

  13. Show Me What You Know Movement of particles from an area of higher concentration to one of lower concentration is ______________? Diffusion

  14. Show Me What You Know Which of the following structures is the most complex? • Cell • Organ System • Organ • Tissue

  15. Show Me What You Know Which of the following structures is the most complex? • Cell • Organ System • Organ • Tissue

  16. Activity • Write your summary of notes • On the left hand side of your notebook, draw and label a phospholipid bilayer. Use p. 177-178 of your text. Don’t forget to add color.

  17. Plasma Membrane Day Two

  18. Cell Transport • 2 types of cell transport: • Passive Transport: Movement of particles across a membrane requiring NO energy • High concentration  Low concentration • Active Transport:

  19. Passive Transport: Osmosis • Osmosis: diffusion of H2O across a selectively permeable membrane. • Ex. If membrane that only allows water to pass through, water will diffuse to side where H2O concentration is lower and will continue until equal concentration is reached on both sides

  20. Passive Transport: Osmosis • Isotonic Solution: Concentration is the same both insideandoutside the cell • Hypotonic Solution: concentration is lower outside than inside the cell • Hypertonic Solution: concentration is higheroutside than inside the cell

  21. Passive Transport: Osmosis

  22. Passive Transport: Diffusion • Diffusion: net movement of particles from higher concentration to lower. • Results from random movement of particles running into one another • Very slow process because it relies on random motion

  23. Continued • 3 key factors: • Concentration: Increase in concentration will increase the rate of diffusion • Temperature: Increase in temperature will increase rate of diffusion • Pressure: Increase in pressure will increase rate of diffusion • Dynamic Equilibrium: continuous movement with no overall concentration change

  24. Passive Transport: Diffusion

  25. Active Transport • Active Transport: Movement of materials through a membrane against a concentration gradient (requires energy)

  26. Active Transport: Carrier Transport Proteins • Carrier Proteins: • Bind with particle of the substance to be transported • Lock and Key!! • With the right fit, chemical energy allows shape of carrier protein to change releasing particle on other side • Much like the action of a door

  27. Active Transport: Carrier Proteins

  28. Active Transport: Endocytosis • Endocytosis occurs when the cell surrounds and takes in large material from it’s environment • Does not pass through membrane • Engulfed and enclosed by part of the PM • Membrane breaks away creating a vacuole with the material inside • Phagocytosis: cell brings in a solid • Pinocytosis: cell brings in liquid

  29. Active Transport: Exocytosis • Exocytosis occurs when the cell expels or secretes large particles from the cell • Ex. wastes, hormones

  30. Show Me What You Know Water moves into a cell placed in a(n) __________ solution. • Osmotic • Hypertonic • Hypotonic • Isotonic

  31. Show Me What You Know Water moves into a cell placed in a(n) __________ solution. • Osmotic • Hypertonic • Hypotonic • Isotonic

  32. Show Me What You Know Water moves out of a cell if the cell is placed in a(n) ___________ solution. • Hypertonic • Isotonic • Hyptonic • passive

  33. Show Me What You Know Water moves out of a cell if the cell is placed in a(n) ___________ solution. • Hypertonic • Isotonic • Hyptonic • passive

  34. Show Me What You Know A cell moves particles from a region of lesser concentration to a region of greater concentration by ____________. • Facilitated diffusion • Passive transport • Osmosis • Active Transport

  35. Show Me What You Know A cell moves particles from a region of lesser concentration to a region of greater concentration by ____________. • Facilitated diffusion • Passive transport • Osmosis • Active Transport

  36. Activity • Write a summary for your notes • Create a foldable to be glued into the activity page of your notebook. Use p. 195 of your text to create the foldable. Don’t forget to use at least 4 colors

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