Chapter 4 Lecture 4

8/3/2019 Chapter 4 Lecture 4

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Prof. T. L. Frison

Cell Phones OffPlease!!

No food or drinks!


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4.1 Plasma Membrane Structure

and Function

Regulates the entrance and exit of molecules into and

out of the cell Phospholipid bilayer with embedded proteins

Hydrophilic polar heads

Hydrophobic nonpolar tails

Cholesterol (animal cells)


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Fluid-mosaic Model of Plasma

Membrane Structure


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4.1 Plasma Membrane Structure

and Function Types of Membrane Proteins

Channel Proteins

Carrier Proteins Cell Recognition Proteins

Receptor Proteins

Enzymatic


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Proteins


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4.2 Permeability of the Plasma

Membrane

Differentially (selectively) Permeable

Factors that determine how a substance may betransported across a plasma membrane:

Size

Polar or Nonpolar


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How Molecules Cross the Plasma

Membrane


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Passage of Molecules into and out

of the Cell


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Membrane Diffusion and Osmosis


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Diffusion is the movement of molecules from an area ofhigher to lower concentration


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Process of Diffusion


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Diffusion is the movement of molecules from an area ofhigher to lower concentration

Oxygen and Carbon Dioxide are two gases that candiffuse through the plasma membrane


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Gas Exchange in Lungs


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Membrane Osmosis

Osmosis is the diffusion of water across a differentiallypermeable membrane.


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Membrane Osmosis

Osmosis is the diffusion of water across a differentiallypermeable membrane.

Osmotic pressure is the pressure that develops in asystem due to osmosis.


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Osmosis Demonstration


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Membrane Osmosis

Isotonic: the solute concentration isequal inside and outside of a cell


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Membrane Osmosis


Hypotonic: a solution has a lower soluteconcentration than the insideof a cell


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Membrane Osmosis


Hypotonic: a solution has a lower soluteconcentration than the insideof a cell

Hypertonic: a solution has a higher soluteconcentration than the insideof a cell


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Osmosis in Animal

and Plant Cells


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Membrane Transport by Carrier Proteins

Carrier proteins combine with a molecule or ion to betransported across the membrane.


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Carrier proteins are required for:

Facilitated Transport


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Carrier proteins are required for:

Facilitated Transport

Active Transport


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MembraneActive Transport

Small molecules

Molecules combine with carrier proteins Molecules move against the concentration gradient

ATP is required


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The Sodium-Potassium Pump


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MembraneVesicle Formation

Transport of large molecules

Requires ATP energy Keeps the macromolecule contained


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MembraneVesicle Formation

Exocytosis - Vesicles form as a way to transportmolecules out of a cell


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Exocytosis


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Vesicle Formation

Endocytosis - Vesicles form as a way to transportmolecules into a cell


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Vesicle FormationVesicle Formation

Endocytosis - Vesicles form as a way to transportmolecules into a cell Phagocytosis: Large,particulate matter


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Vesicle FormationVesicle Formation

Endocytosis - Vesicles form as a way to transportmolecules into a cell Phagocytosis: Large,particulate matter

Pinocytosis: Liquids and small particles dissolved in liquid


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Chapter 4 Lecture 4

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