Cell BoundariesChapter 6
What are boundaries? We have borders  surrounding  countries We have boundaries  on a playing field Why are borders  im...
What are the borders of acell?  Cell membrane    Thin, flexible barrier  Cell wall    Plant, algae, fungi, prokaryotes...
Cell Membrane  What does it do for cell?    Controls what goes in and out       Regulates molecules moving from one liq...
Cell Membrane Lipid bilayer    What are lipids?    What does bi- mean?    What’s a layer? A cell membrane is made of ...
Cell membrane Phospholipids bilayer   Made of a negatively charged    phosphate “head”      PO43-      Attracts water ...
Other things in themembrane…  Proteins embedded   in lipid bilayer  Carbohydrates   attached to proteins  So many diffe...
Proteins  Proteins help things   get across   membrane  Kinda like a pump
Carbohydrates…  Chemical   identification cards  “ID” card of cell  Helps individual cells   id each other
Cell Walls Outside cell membrane  (does NOT replace  membrane!!!) Plants, algae, fungi,  prokaryotes Have pores to allo...
Cell walls made of…  Protein and carbs  Plant cell walls made   up of CELLULOSE    This is a tough     carbohydrate   ...
The Cell Membrane   A biological membrane   Cells exist in liquid environments   Things need to get in and out of cell...
Concentration (conc.) Solution    Mix of 2 or more substances Solutes    Substance dissolved in solution Concentratio...
Diffusion Particles constantly move Collide randomly Spread out randomly Diffusion is moving from area of HIGH conc. t...
Equilibrium  When the conc. Of a   system is the same   throughout  (same conc. on both   sides)
What happens when we  reach equilibrium? Particles continue moving across membrane but in  both directions!  ***No more c...
If things can cross amembrane we call themembrane PERMEABLEIf things canNOT cross amembrane we call themembrane IMPERMEABLE
Biological membranesare…    SEMI-PERMEABLE    A.K.A.    Selectively permeable    Cell membranes are picky
What’s this have to dowith cells?  Cell have liquid inside and are found in liquid   environment  We have substances (so...
What diffuses across themembrane??? Small, uncharged  (non-polar) molecules Examples:   Carbon dioxide   Oxygen
Cells are always trying to Maintain Equilibrium by…3 ways… PASSIVE Transport                                     ACTIVE ...
Osmosis Water (H2O) can pass easily through most  biological membranes Def:   Diffusion of Water through a semi-permeab...
How Osmosis works… We have water molecules and some other molecules, let’s  say sugar If we have more water on one side ...
Water moves from areas of HIGH conc. To areas of LOW conc. Water moves across till equilibrium is reached Isotonic:   w...
Osmotic Pressure Central vacuole fills with water and exerts and  out ward pressure on cell membrane and cell  wall Cell...
Problems in Plant Cell
Osmotic Pressure Pressure exerted by osmosis on the  HYPERTONIC side of a semi-permeable  membrane   Think about blowing...
Why don’t all our cells burst? What are our cells (animal) contained in?   Fresh water?   No…..blood or other fluids, w...
 Which is a RBC in isotonic solution? RBC in hypertonic solution? RBC in hypotonic solution?
How do big moleculesdiffuse across a membraneso quickly if the membraneis selectively permeable?
Problems for diffusion… Things too large (like Glucose!) Charged molecules and Polar molecules   Positive/negative   O...
Facilitated Diffusion   What does facilitate mean?   Proteins are the extra help   “escorts” across the membrane   We ...
Facilitated Diffusion•takes place through proteins, or assemblies of proteins, embedded inthe plasma membrane        Prote...
Facilitated Diffusion(continued) FAST SPECIFIC Still diffusion  so we only see  it from high  concentration  to low Do...
What about when we want togo against theconcentration?(From low concentration tohigh?)
What do we need??? ENERGY!!!!
ACTIVE transport Process that moves molecules against the concentration gradient Requires ENERGY A protein pumps small ...
Build up of Na+ ions on one side of membrane from Na+/K+ pumpNow Na+ will flow thru another channel that allows one glucos...
Endocytosis  When cells need to take in large material  Process of taking material into the cell by   process of infoldi...
Two types of endocytosis:1. Phagocytosis   “cell eating”   Extensions of cytoplasm surround the particle    and package ...
Exocytosis  Exo- means…  Cyto means…  Sis means…  When cell releases large amounts of material  Excretes stuff  Memb...
Cells are always trying to Maintain Equilibrium by…3 ways… PASSIVE Transport                                     ACTIVE ...
MEMBRANE MAMBO!!!
Membrane Mambo   10 minutes to plan   2 teams/Cells   Nucleus for each team   Each member must be assigned a molecular...
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Cell membrane powerpoint diffusion and osmosis revised
Upcoming SlideShare
Loading in …5
×

Cell membrane powerpoint diffusion and osmosis revised

484 views

Published on

Published in: Technology, Education
1 Comment
0 Likes
Statistics
Notes
  • Be the first to like this

No Downloads
Views
Total views
484
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
15
Comments
1
Likes
0
Embeds 0
No embeds

No notes for slide

Cell membrane powerpoint diffusion and osmosis revised

  1. 1. Cell BoundariesChapter 6
  2. 2. What are boundaries? We have borders surrounding countries We have boundaries on a playing field Why are borders important?
  3. 3. What are the borders of acell?  Cell membrane  Thin, flexible barrier  Cell wall  Plant, algae, fungi, prokaryotes  Strong supporting layer
  4. 4. Cell Membrane  What does it do for cell?  Controls what goes in and out  Regulates molecules moving from one liquid side of the cell to the other liquid side of the cell  Protects  Supports
  5. 5. Cell Membrane Lipid bilayer  What are lipids?  What does bi- mean?  What’s a layer? A cell membrane is made of two layers of lipid molecules
  6. 6. Cell membrane Phospholipids bilayer  Made of a negatively charged phosphate “head”  PO43-  Attracts water because the phosphate is charged (-)  Water is a polar , slightly positive ends and slightly negative ends  Attached to the phosphate group are 2 fatty acid chains  Hydrophobic= don’t like water  So the inside of the cell membrane doesn’t let water in but the outside allows cells to be dissolved in aqueous environments
  7. 7. Other things in themembrane…  Proteins embedded in lipid bilayer  Carbohydrates attached to proteins  So many different molecules in membrane, we call it a “mosaic” of different molecules
  8. 8. Proteins  Proteins help things get across membrane  Kinda like a pump
  9. 9. Carbohydrates…  Chemical identification cards  “ID” card of cell  Helps individual cells id each other
  10. 10. Cell Walls Outside cell membrane (does NOT replace membrane!!!) Plants, algae, fungi, prokaryotes Have pores to allow things in Function: SUPPORT and PROTECT
  11. 11. Cell walls made of…  Protein and carbs  Plant cell walls made up of CELLULOSE  This is a tough carbohydrate  Wood and paper
  12. 12. The Cell Membrane A biological membrane Cells exist in liquid environments Things need to get in and out of cell Different ways to do this….
  13. 13. Concentration (conc.) Solution  Mix of 2 or more substances Solutes  Substance dissolved in solution Concentration  Molarity (M) is # of Moles of a substance per liter of solution  6.02 x 1023 “small things” (molecules, atoms, ions, electrons, ions, etc)  Moles is a unit for measuring EXTREMELY small things is mass of SOLUTE in a given volume of solution (g/L) What is the concentration of 12 grams of salt dissolved in 3 liters of water?  12g/3L= 4g/L
  14. 14. Diffusion Particles constantly move Collide randomly Spread out randomly Diffusion is moving from area of HIGH conc. to area of LOW conc. This is what we call the CONCENTRATION GRADIENT
  15. 15. Equilibrium  When the conc. Of a system is the same throughout  (same conc. on both sides)
  16. 16. What happens when we reach equilibrium? Particles continue moving across membrane but in both directions! ***No more changes in concentration
  17. 17. If things can cross amembrane we call themembrane PERMEABLEIf things canNOT cross amembrane we call themembrane IMPERMEABLE
  18. 18. Biological membranesare…  SEMI-PERMEABLE  A.K.A.  Selectively permeable  Cell membranes are picky
  19. 19. What’s this have to dowith cells?  Cell have liquid inside and are found in liquid environment  We have substances (solutes) inside and outside cell  Unequal concentrations means we get DIFFUSION!!!  B/c diffusion depends on random particle movements, substances diffuse across membranes without requiring the cell to use energy
  20. 20. What diffuses across themembrane??? Small, uncharged (non-polar) molecules Examples:  Carbon dioxide  Oxygen
  21. 21. Cells are always trying to Maintain Equilibrium by…3 ways… PASSIVE Transport  ACTIVE Transport 2 types  1 type Requires NO energy  REQUIRES Energy Goes with Conc. Gradient  Goes Against Conc. Gradient types:  ACTIVE TRANSPORT  SIMPLE DIFFUSION-  Involves “transporter”  No protein required membrane protein and  Small, uncharged particles ENERGY (ATP)  FACILITATED DIFFUSION-  CHANNEL or CARRIER proteins  Trans-membrane protein channel  Protein with a specific shape; open-close mechanism  Ex. Osmosis and ligand-gated channels
  22. 22. Osmosis Water (H2O) can pass easily through most biological membranes Def:  Diffusion of Water through a semi-permeable membrane  Small molecules of water can sometimes diffuse across easily (no protein needed)  AQUAPORIN:  What does “aqua” mean???  Protein in cell membrane that allows water through (speeds up diffusion of water across the membrane)  Type of Facilitated diffusion (more on this later)
  23. 23. How Osmosis works… We have water molecules and some other molecules, let’s say sugar If we have more water on one side of the membrane (HIGH conc. of H2O), then the water will diffuse across… Membrane will let water thru but not sugar Water can move back and forth (not sugar)
  24. 24. Water moves from areas of HIGH conc. To areas of LOW conc. Water moves across till equilibrium is reached Isotonic:  when conc. Of both solutions is equal Hypertonic: “above strength”  When we begin with more sugar in water  More concentrated sugar solution on side A Hypotonic: “below strength”  When we end with less sugar  Dilute sugar solution on side A
  25. 25. Osmotic Pressure Central vacuole fills with water and exerts and out ward pressure on cell membrane and cell wall Cell wall does NOT allow cell to expand past a certain sizeOsmoregulation  Osmoregulation  means by which cells keep the concentration of cell cytoplasm or blood at a suitable concentration.
  26. 26. Problems in Plant Cell
  27. 27. Osmotic Pressure Pressure exerted by osmosis on the HYPERTONIC side of a semi-permeable membrane  Think about blowing up a balloon… Can cause serious problems for cell  Cell is full of sugar, salts, proteins, molecules  Inside of cell is Hypertonic  Osmotic pressure should make fresh water go…?  In or Out?  In  Cell will become inflated/swollen  Too much cell will burst like a balloon
  28. 28. Why don’t all our cells burst? What are our cells (animal) contained in?  Fresh water?  No…..blood or other fluids, which are ISOTONIC  The conc. Of sugars, salts, proteins and molecules in these fluids is the same as the conc. in the cell Bacteria and plant cells  They DO come in contact with fresh water…what do they have PROTECTING them?  CELL WALL  Prevent cells from expanding even when there’s a lot of osmotic pressure  But, cell walls are prone to injuries when there is too much osmotic pressure
  29. 29.  Which is a RBC in isotonic solution? RBC in hypertonic solution? RBC in hypotonic solution?
  30. 30. How do big moleculesdiffuse across a membraneso quickly if the membraneis selectively permeable?
  31. 31. Problems for diffusion… Things too large (like Glucose!) Charged molecules and Polar molecules  Positive/negative  Opposites attract but likes do not…  These all present serious problems for things getting across membranes…
  32. 32. Facilitated Diffusion What does facilitate mean? Proteins are the extra help “escorts” across the membrane We call these membrane proteins…  Protein channels  Carrier proteins  LIGAND receptor proteins
  33. 33. Facilitated Diffusion•takes place through proteins, or assemblies of proteins, embedded inthe plasma membrane Protein channels Carrier proteins LIGAND receptor proteins
  34. 34. Facilitated Diffusion(continued) FAST SPECIFIC Still diffusion so we only see it from high concentration to low Does NOT require energy
  35. 35. What about when we want togo against theconcentration?(From low concentration tohigh?)
  36. 36. What do we need??? ENERGY!!!!
  37. 37. ACTIVE transport Process that moves molecules against the concentration gradient Requires ENERGY A protein pumps small molecules and ions across a cell membrane against the conc. Gradient Direct and Indirect Active transport (see animation)  Forms of molecular transport proteins are used to pump small molecules and ions across membrane even against the conc. grad.  Direct: every 3 Na+ ions pumped across for every 2 K+ ions  Indirect: Build up of ions on one side opens up another channel to shuttle in other molecules (Na+/Glucose channel) Electrochemical gradient  membrane potential (cell membrane is negative)  Na+ opens build up on the outside of the cell…draws water out of the cell so it doesn’t swell or burst! To pump large molecules and clumps…  2 other processes:  Exocytosis: exo-means….cyto- means…..-sis means….  Endocytosis: endo-means….cyto- means…..-sis means….  They can change shape of membrane
  38. 38. Build up of Na+ ions on one side of membrane from Na+/K+ pumpNow Na+ will flow thru another channel that allows one glucose intoo!Pretty convenient!
  39. 39. Endocytosis  When cells need to take in large material  Process of taking material into the cell by process of infolding, or pockets, of the cell membrane  Pocket breaks loose from cell membrane and forms a vacuole or vesicle inside the cell  Two Types…  Phagocytosis  Pinocytosis
  40. 40. Two types of endocytosis:1. Phagocytosis  “cell eating”  Extensions of cytoplasm surround the particle and package it within a food vesicle  Cell then engulfs the package  Amoebas2. Pinocytosis  “cell drinking”  When cell needs to take up liquid  Tiny pockets in cell membrane form  Fill with liquid or many smaller molecules  Then pinch off to form vesicles inside of cell
  41. 41. Exocytosis  Exo- means…  Cyto means…  Sis means…  When cell releases large amounts of material  Excretes stuff  Membrane of vacuole surrounding particle inside cell fuses with the cell membrane  The contents in vacuole are then forced out of the cell  We see this in removal of water by contractile vacuoles
  42. 42. Cells are always trying to Maintain Equilibrium by…3 ways… PASSIVE Transport  ACTIVE Transport 2 types  1 type Requires NO energy  REQUIRES Energy Goes with Conc. Gradient  Goes Against Conc. Gradient types:  ACTIVE TRANSPORT  SIMPLE DIFFUSION-  Involves “transporter”  No protein required membrane protein and  Small, uncharged particles ENERGY (ATP)  FACILITATED DIFFUSION-  CHANNEL or CARRIER proteins  Trans-membrane protein channel  Protein with a specific shape; open-close mechanism  Ex. Osmosis and ligand-gated channels
  43. 43. MEMBRANE MAMBO!!!
  44. 44. Membrane Mambo 10 minutes to plan 2 teams/Cells Nucleus for each team Each member must be assigned a molecular role (must be labeled)  Membrane protein(s)  Molecule A (ex. Glucose)  Molecule B (ex. Na+)  Molecule C (ex. Water)  Remember molecules are ALWAYS moving!!! MUST act out the following types of membrane transport:  Simple Diffusion  Osmosis  Facilitated diffusion (channel, carrier and ligand)  Active transport (direct and indirect) Be prepared to determine the concentration on either side of the membrane Your “Nucleus” must turn in a paper with every ones name and roles Summary of how each scenario will be acted out

×