1 The Plasma Membrane The Plasma Membrane - copyright cmassengale

2 Photograph of a Cell Membrane copyright cmassengale

3 Cell Membrane controls what comes into and goes out of a cell. The cell membrane controls what comes into and goes out of a cell. copyright cmassengale

4 Structure of the Cell Membrane copyright cmassengale Surface Protein Transport (Channel) Protein Phosphate Heads Lipid Tails

Phospholipid Bilayer 5 Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Phospholipids are arranged in a bilayer, with the tails facing inward and the heads facing outward.

6 Phospholipids Phosphate Head Hydrophobic or “Water-fearing” Non-polar Hydrophilic or “Water-Loving” Polar copyright cmassengale Lipid Tail (fatty acid)

7 hydrophilic Heads are hydrophilic “water loving ” hydrophobic Tails are hydrophobic “water fearing” Cell Membrane Makes membrane “Selective” in what crosses copyright cmassengale

8 Selective Permeability These molecules pass easily; EX. O 2, CO 2, H 2 O they pass through the lipids copyright cmassengale These DO NOT EX. Ions, proteins they can’t pass through the lipids

9 The Cell Membrane is Fluid Molecules in cell membranes are constantly moving and changing. copyright cmassengale

The Membrane is called the Fluid Mosaic Model –Parts of the membrane “float” around and are NOT fixed in place –It has proteins on the surface and through it Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains

11 Membrane Proteins copyright cmassengale

12 Membrane Protein Functions copyright cmassengale

13 Recognize “self” GLYCOPROTEINS Glycoproteins have carbohydrate tails to act as markers for cell recognition & cell signaling.

14 CHOLESTEROL Cholesterol helps maintain structural stability.

15 Cell Membrane controls what comes into and goes out of a cell. The cell membrane controls what comes into and goes out of a cell. copyright cmassengale

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

17 How does the plasma membrane maintain homeostasis? copyright cmassengale

18 Three Forms of Transport Across the Membrane Materials move across the bilayer from a HIGH concentration to a LOW concentration. Materials move through a Transport Protein from a HIGH concentration to a LOW concentration. Materials move through a Transport Protein from a LOW concentration to a HIGH concentration. (REQUIRES ENERGY)

copyright cmassengale19 Substances crossing the membrane WITHOUT the use of energy.

First, some REVIEW words. copyright cmassengale20 DIFFUSION The passive movement of particles from an area of high concentration to an area of low concentration OSMOSIS The passive movement of water from an area of lower solute concentration to an area of higher solute concentration

Let’s review a couple of words. copyright cmassengale21 Solution: A mixture of 2 or more substances Solute: the substance that is dissolved Solvent: the substance in which the solute is dissolved

Examples copyright cmassengale22 In saltwater, the solute is ______ and the solvent is _________. In Kool-Aid, the solutes are the ______________ and _____________. The solvent is ___________. salt water sugar powder water

23 Diffusion NORequires NO energy (passive) HIGH to LOWMolecules move from area of HIGH to LOW concentration copyright cmassengale

24 Diffusion of Liquids copyright cmassengale

25 Diffusion through a Membrane Cell membrane Solute moves from HIGH concentration to LOW concentration

26 Passive Transport Simple Diffusion  Examples:  Oxygen diffusing into a cell  carbon dioxide diffusing out  carbon dioxide diffusing out. copyright cmassengale

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

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

3 types of solutions copyright cmassengale29 Hypertonic Hypotonic Isotonic

“hyper” = above Hypertonic solution= has a higher concentration

cell Hypertonic Solution 4% sugar solution 2% sugar

“hypo” = below Hypotonic solution= has a lower concentration

cell Hypotonic Solution 1% sugar solution 2% sugar

“iso” = equal Isotonic solution= has the same concentration

cell Isotonic Solution 2% sugar solution 2% sugar

Ok, let’s practice what we’ve just learned... Number on your paper.

1. _________? Solution cell 1% sugar solution 2% sugar Practice Hypotonic

cell 2. _________? Solution 2% sugar solution 2% sugar Practice Isotonic

cell 3. _________? Solution 5% sugar solution 7% sugar Practice Hypotonic

Jose dissolves 1 gram of gelatin powder into 100 mL of water and pours it into the beaker below. 1.0% gelatin solution 4. What is the solvent in this solution? ______ Practice Water

1.0% gelatin solution 5. What is the solute in Jose’s solution? ______ Practice Gelatin Powder

cell 6. _________? Solution 1.5% sugar solution 1.0% sugar Practice Hypertonic

cell 7. Which solution is hypertonic? 3.8% sugar solution 3.2% sugar Practice The outside one

cell 8. Which solution is hypotonic? 1.5% sugar solution 0.5% sugar Practice Inside the cell

End Practice

3 types of solutions copyright cmassengale46 Hypertonic Hypotonic Isotonic

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

48 So, how does this affect CELLS? copyright cmassengale

49 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic copyright cmassengale

50

51 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 Shrivels!

52 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 Explodes!

53 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 copyright cmassengale Stays the same!

54 Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution Cell explodes! Hypertonic Solution Cell shrivels! copyright cmassengale Water IN Water OUT

Tonicity and Osmosis Worksheet copyright cmassengale55

56 Passive Transport Facilitated diffusion  Doesn’t require energy  Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell. copyright cmassengale

57 Facilitated Diffusion Molecules will diffuse through the Integral Proteins. copyright cmassengale

58 Substances crossing the membrane WITH the use of energy.

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

60 Active transport  Examples: Pumping Na + (sodium ions) out and K + (potassium ions) in against the concentration gradient.  Called Sodium- Potassium Pump copyright cmassengale

61 Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out copyright cmassengale ActiveTransportDemo

62 Three Forms of Transport Across the Membrane Materials move across the bilayer from a HIGH concentration to a LOW concentration. Materials move through a Transport Protein from a HIGH concentration to a LOW concentration. Materials move through a Transport Protein from a LOW concentration to a HIGH concentration. (REQUIRES ENERGY)

copyright cmassengale63 What about the big stuff? Endocytosis – large substances coming in; infolding of the membrane. Exocytosis – large substances going out; vesicles fuse with the membrane

64Endocytosis Cells taking in materials, forming vesicles Cells taking in materials, forming vesicles.

65Endocytosis 1.Pinocytosis – taking in liquids “Cell Drinking” copyright cmassengale

66 Example of Pinocytosis pinocytic vesicles forming mature transport vesicle Also called “Cell Drinking” copyright cmassengale

67Endocytosis 2. Phagocytosis – taking in solids “Cell Eating” copyright cmassengale

68 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles copyright cmassengale

69 Phagocytosis About to Occur copyright cmassengale

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

71Exocytosis Molecules are moved out of the cell by vesicles that fuse with the cell membrane.

72copyright cmassengale

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

74 What about the big stuff? In each of these cases, the membranes are able to form and break without the loss of continuity of the plasma membrane.

copyright cmassengale75 Li Yang & Huey Huang Model a)Membranes approach b)Membranes touch c)At point of contact, there is one bilayer. d)Membranes become continuous.

copyright cmassengale76 Let’s Review! Passive Transport Simple Diffusion Osmosis Facilitated Diffusion REQUIRES NO ENERGY! HIGH conc. to LOW conc.

copyright cmassengale77 Active Transport Pump Endocytosis Phagocytosis Pinocytosis Exocytosis REQUIRES ENERGY LOW conc. to HIGH conc. Let’s Review!