Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 The Plasma Membrane The Plasma Membrane - Gateway to the Cell copyright cmassengale.

Similar presentations


Presentation on theme: "1 The Plasma Membrane The Plasma Membrane - Gateway to the Cell copyright cmassengale."— Presentation transcript:

1 1 The Plasma Membrane The Plasma Membrane - Gateway to the Cell copyright cmassengale

2 2 Photograph of a Cell Membrane copyright cmassengale

3 3 Cell Membrane flexible The cell membrane is flexible and allows a unicellular organism to move copyright cmassengale

4 4 Homeostasis Balanced internal condition of cells Also called equilibrium Maintained by plasma membrane controlling what enters & leaves the cell copyright cmassengale

5 5 Functions of Plasma Membrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Provide anchoring sites for filaments of cytoskeleton copyright cmassengale

6 6 Functions of Plasma Membrane Provide a binding site for enzymes Interlocking surfaces bind cells together (junctions) Interlocking surfaces bind cells together (junctions) Contains the cytoplasm (fluid in cell) Contains the cytoplasm (fluid in cell) copyright cmassengale

7 7 Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT phospholipid bilayer The cell membrane is made of 2 layers of phospholipids called the lipid bilayer copyright cmassengale

8 8 Phospholipids Make up the cell membrane Contains 2 fatty acid chains that are nonpolar Head is polar & contains a –PO 4 group & glycerol copyright cmassengale

9 9

10 10 hydrophilic Polar heads are hydrophilic water loving hydrophobic Nonpolar tails are hydrophobic water fearing Cell Membrane Makes membrane Selective in what crosses copyright cmassengale

11 11 FLUID- because individual phospholipids and proteins can move around freely within the layer, like its a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above. FLUID MOSAIC MODEL copyright cmassengale

12 12 Small molecules and larger hydrophobic molecules move through easily. e.g. O 2, CO 2, H 2 O Semipermeable Membrane copyright cmassengale

13 13 Phospholipids Phospholipids Cholesterol Proteins -peripheral- (on the edge of the membrane)and integral- (also called intrinsic proteins, they are embedded in the phospholipid bilayer) Membrane Components copyright cmassengale

14 14 Proteins are important structures in the cell membrane copyright cmassengale Glyco –means of or relating to sugar Glycoproteins have the carbohydrate chain (They are also called Marker Proteins) they identify the cell- they are not transport proteins.

15 Glycolipids are lipids with carbohydrate chains attached. Their main function is to provide energy and serve as markers for cellular recognition. copyright cmassengale15

16 What is the difference between glyco-proteins and glyco-lipids? Glycoproteins are NOT energy storage molecules, they function in cell-cell recognition pathways. (They are marker proteins.) Glycolipids are energy storage molecules and they also those function in recognition, mostly in vesicle trafficking pathways inside the cell, not in recognition between different cells. They both have carbohydrate chains (This will not be on your test.) copyright cmassengale16

17 Cell membrane components copyright cmassengale17

18 18 Solubility Materials that are soluble in lipids can pass through the cell membrane easily copyright cmassengale

19 19 Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. Semipermeable Membrane copyright cmassengale

20 20 Types of Transport Across Cell Membranes copyright cmassengale

21 21 Simple Diffusion NORequires NO energy HIGH to LOWMolecules move from area of HIGH to LOW concentration copyright cmassengale

22 22 DIFFUSION PASSIVE Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY copyright cmassengale

23 23 Diffusion of Liquids copyright cmassengale

24 24 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) copyright cmassengale

25 25 Osmosis Diffusion of water across a membraneDiffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute)Moves from HIGH water potential (low solute) to LOW water potential (high solute) Diffusion across a membrane Semipermeable membrane copyright cmassengale

26 26 Diffusion of H 2 O Across A Membrane High H 2 O potential Low solute concentration Low H 2 O potential High solute concentration copyright cmassengale

27 27 Cell in Isotonic Solution CELL 10% NaCL 90% H 2 O 10% NaCL 90% H 2 O What is the direction of water movement? The cell is at _______________. equilibrium ENVIRONMENT NO NET MOVEMENT copyright cmassengale

28 28 Cell in Hypotonic Solution CELL 10% NaCL 90% H 2 O 20% NaCL 80% H 2 O What is the direction of water movement? copyright cmassengale

29 29 Cell in Hypertonic Solution CELL 15% NaCL 85% H 2 O 5% NaCL 95% H 2 O What is the direction of water movement? ENVIRONMENT copyright cmassengale

30 30 Cells in Solutions copyright cmassengale

31 31 Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution CYTOLYSIS Hypertonic Solution PLASMOLYSIS copyright cmassengale

32 32 Cytolysis & Plasmolysis Cytolysis Plasmolysis copyright cmassengale

33 33 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic copyright cmassengale

34 34 hypotonichypertonic isotonic hypertonicisotonic hypotonic copyright cmassengale

35 35 Three Forms of Transport Across the Membrane copyright cmassengale

36 36 Passive Transport Simple Diffusion Doesnt require energy Doesnt require energy Moves high to low concentration Moves high to low concentration Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out. copyright cmassengale

37 37 Passive Transport Facilitated diffusion Doesnt require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell. copyright cmassengale

38 38 Proteins Are Critical to Membrane Function copyright cmassengale

39 39 Types of Transport Proteins Channel proteins are embedded in the cell membrane & have a pore for materials to cross Receptor or carrier proteins can change shape to move material from one side of the membrane to the other copyright cmassengale

40 40 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. copyright cmassengale

41 41 Facilitated Diffusion Some Carrier proteins do not extend through the membrane.Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side.They bond and drag molecules through the lipid bilayer and release them on the opposite side. copyright cmassengale

42 42 Receptor or Carrier Proteins Other carrier proteins change shape to move materials across the cell membraneOther carrier proteins change shape to move materials across the cell membrane copyright cmassengale

43 43 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient copyright cmassengale

44 44 Active transport Examples: Pumping Na + (sodium ions) out and K + (potassium ions) in against strong concentration gradients. Called Na+-K+ Pump Helps muscle cells contract. copyright cmassengale

45 45 Sodium-Potassium Pump & Transport Protein- Active Transport using ATP Active Transport using ATP pumping against the gradient. 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential. copyright cmassengale

46 46 Moving the Big Stuff Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. Exocytosis Exocytosis - moving things out. This is how many hormones are secreted and how nerve cells communicate with one another This is how many hormones are secreted and how nerve cells communicate with one another. copyright cmassengale

47 47 Exocytosis Exocytic vesicle immediately after fusion with plasma membrane. copyright cmassengale

48 48 Moving the Big Stuff Large molecules move materials into the cell by one of three forms of endocytosis Large molecules move materials into the cell by one of three forms of endocytosis. copyright cmassengale

49 49Pinocytosis Most common form of endocytosis Most common form of endocytosis. Takes in dissolved molecules as a vesicle Takes in dissolved molecules as a vesicle. copyright cmassengale

50 50 Pinocytosis Cell forms an indentionCell forms an indention Materials dissolve in water to be brought into cellMaterials dissolve in water to be brought into cell Called Cell DrinkingCalled Cell Drinking copyright cmassengale

51 51 Example of Pinocytosis pinocytic vesicles forming mature transport vesicle Transport across a capillary cell (blue). copyright cmassengale

52 52 Receptor-Mediated Endocytosis Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc. copyright cmassengale

53 53 Receptor-Mediated Endocytosis copyright cmassengale

54 54 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called Cell Eating copyright cmassengale

55 55 Phagocytosis About to Occur copyright cmassengale

56 56 Phagocytosis Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue) copyright cmassengale

57 57 Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment copyright cmassengale

58 58copyright cmassengale Now go to classzone.com and go to Ch 3 1.) Go to Research Center and watch the Animations on Active Transport 2.)Watch the Ch 3 Animations – on Cell Structures and Get through a cell membrane 2.)Take the Section Quizzes


Download ppt "1 The Plasma Membrane The Plasma Membrane - Gateway to the Cell copyright cmassengale."

Similar presentations


Ads by Google