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Membrane Transport. 2 Cell or Plasma Membrane Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate.

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Presentation on theme: "Membrane Transport. 2 Cell or Plasma Membrane Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate."— Presentation transcript:

1 Membrane Transport

2 2 Cell or Plasma Membrane Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Composed of double layer of phospholipids and proteins (phospholipid bilayer) Composed of double layer of phospholipids and proteins (phospholipid bilayer) Surrounds outside of ALL cells Surrounds outside of ALL cells Controls what enters or leaves the cell Controls what enters or leaves the cell Living layer Living layer copyright cmassengale

3 3 Phospholipids Heads contain glycerol & phosphate and are hydrophilic (attract water) Heads contain glycerol & phosphate and are hydrophilic (attract water) Tails are made of fatty acids and are hydrophobic (repel water) Tails are made of fatty acids and are hydrophobic (repel water) Make up a bilayer where tails point inward toward each other Make up a bilayer where tails point inward toward each other Can move laterally to allow small molecules (O 2, CO 2, & H 2 O to enter) Can move laterally to allow small molecules (O 2, CO 2, & H 2 O to enter) copyright cmassengale

4 4 Cell Membrane Proteins Proteins help move large molecules or aid in cell recognition Proteins help move large molecules or aid in cell recognition Peripheral proteins are attached on the surface (inner or outer) Peripheral proteins are attached on the surface (inner or outer) Integral proteins are embedded completely through the membrane Integral proteins are embedded completely through the membrane copyright cmassengale

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6 6 The Cell Membrane is also referred to as the Fluid Mosaic Model Molecules in cell membranes are constantly moving and changing copyright cmassengale

7 Structures Of The Plasma Membrane Phosphate Head: Made of a phosphate group (polar and attracts water) Phosphate Head: Made of a phosphate group (polar and attracts water) Carbohydrate: Used for cell recognition Carbohydrate: Used for cell recognition Membrane Protein: Transports large particles across the cell membrane Membrane Protein: Transports large particles across the cell membrane Cholesteral: Helps stabilize the phospholipids Cholesteral: Helps stabilize the phospholipids Lipid Tails: Made of fatty acids (non-polar and does not attract water) Lipid Tails: Made of fatty acids (non-polar and does not attract water)

8 Diffusion Movement of particles Movement of particles –From high –To Low

9 Diffusion Concentration: the mass of solute (what's being dissolved) in a given volume of solvent (what’s doing the dissolving) Concentration: the mass of solute (what's being dissolved) in a given volume of solvent (what’s doing the dissolving) Equilibrium: the concentration throughout a solution is the same Equilibrium: the concentration throughout a solution is the same

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11 Diffusion ● Concentration gradient: the difference in concentration across a barrier/membrane ● Concentration gradient: the difference in concentration across a barrier/membrane ● Because diffusion depends upon random particle movements, substances diffuse across membranes without requiring the cell to use energy ● Because diffusion depends upon random particle movements, substances diffuse across membranes without requiring the cell to use energy

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13 Osmosis Movement of water Movement of water From high From high to low Across a Across aselectivelypermeablemembrane -selects what moves in and out

14 Osmosis

15 Dynamic Equilibrium Equal concentrations are reached Equal concentrations are reached –Not the same volumes Continued movement across the membrane Continued movement across the membrane Not gain or loss Not gain or loss

16 Osmosis ● Osmosis is the diffusion of water through a selectively permeable barrier. Water will tend to move across the membrane until equilibrium is reached, when this occurs the two solutions will be isotonic, the same. ● Osmosis is the diffusion of water through a selectively permeable barrier. Water will tend to move across the membrane until equilibrium is reached, when this occurs the two solutions will be isotonic, the same. ● When a solution is more concentrated with solute it is said to be hypertonic, whereas a dilute (less concentrated) solution is said to be hypotonic. ● When a solution is more concentrated with solute it is said to be hypertonic, whereas a dilute (less concentrated) solution is said to be hypotonic.

17 Osmosis

18 Isotonic Solutions Iso- equal Iso- equal No change in concentrations No change in concentrations –Water still moves –Same amount of water moves in as moves out Both sides of membrane are the same Both sides of membrane are the same

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20 Hypertonic Solution Hyper- Over Hyper- Over Out side of cell Out side of cell –More dissolved substance –Less water Water moves out of cell Water moves out of cell

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22 Hypotonic Solution Hypo- under Hypo- under Out side of cell Out side of cell –Less dissolved substance –More water Water moves into cell Water moves into cell

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24 Passive Transport Cell uses no energy Cell uses no energy From high to low From high to low Concentration gradient Plasma membrane

25 Facilitated Diffusion Type of passive transport Type of passive transport Use transport Use transportproteins –Channel proteins –Carrier proteins Changes shape Changes shape From high to low From high to low

26 Facilitated Diffusion ● During facilitated diffusion molecules that would not normally be able to cross through the membrane, such as glucose, diffuse across the membrane through selected protein channels. ● During facilitated diffusion molecules that would not normally be able to cross through the membrane, such as glucose, diffuse across the membrane through selected protein channels. It is dependent upon the concentration gradient because it does not require the cell to expend any energy. It is dependent upon the concentration gradient because it does not require the cell to expend any energy.

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28 Active Transport Cell uses energy Cell uses energy Against concentration Against concentrationgradient –From low to high Carrier Proteins Carrier Proteins –Molecule binds with carrier protein –Energy then used to change shape –Molecule released on other side –Carrier protein returns to original shape

29 Active Transport ●The movement of material across a membrane and against a concentration gradient is called active transport. ●The movement of material across a membrane and against a concentration gradient is called active transport. Like facilitated diffusion this is carried out by protein channels in the membrane called transport proteins, however in this form of diffusion energy is expended in the process of “pumping” the material “uphill” against the gradient. Like facilitated diffusion this is carried out by protein channels in the membrane called transport proteins, however in this form of diffusion energy is expended in the process of “pumping” the material “uphill” against the gradient.

30 Molecule to be carried Molecule being carried Energy Active Transport

31 Large Particle Transport ● Endocytosis is the process of taking material into the cell by means of enfolding's, or pockets, of the cell membrane. The pocket or enfold, once it has surrounded the molecule, then closes and breaks off from the membrane forming a vacuole. Two examples of endocytosis are phagocytosis (cell eating) and pinocytosis (cell drinking). ● Endocytosis is the process of taking material into the cell by means of enfolding's, or pockets, of the cell membrane. The pocket or enfold, once it has surrounded the molecule, then closes and breaks off from the membrane forming a vacuole. Two examples of endocytosis are phagocytosis (cell eating) and pinocytosis (cell drinking). ● Exocytosis works the opposite of endocytosis. It is a vacuole with material designated to leave the cell which joins with the cell membrane then releases its material outside of the cell. ● Exocytosis works the opposite of endocytosis. It is a vacuole with material designated to leave the cell which joins with the cell membrane then releases its material outside of the cell.

32 Large Particle Transport (Exocytosis and Endocytosis)

33 Large Particle Transport Not through membrane Not through membrane Requires energy Requires energy Exocytosis- out Exocytosis- out

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35 Large Particle Transport Endocytosis- in Endocytosis- in

36 Types of Endocytosis Pinocytosis: liquid (into) Phagocytosis: Solid (into)

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