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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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A Proteins
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4.2 Permeability of the Plasma Membrane
Differentially (selectively) Permeable Factors that determine how a substance may be transported 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 Know for test
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4.2 Permeability of the Plasma Membrane
Diffusion and Osmosis Diffusion is the movement of molecules from an area of higher to lower concentration
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Process of Diffusion
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4.2 Permeability of the Plasma Membrane
Diffusion and Osmosis Diffusion is the movement of molecules from an area of higher to lower concentration Oxygen and Carbon Dioxide are two gases that can diffuse through the plasma membrane
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Gas Exchange in Lungs
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4.2 Permeability of the Plasma Membrane
Osmosis Osmosis is the diffusion of water across a differentially permeable membrane.
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4.2 Permeability of the Plasma Membrane
Osmosis Osmosis is the diffusion of water across a differentially permeable membrane. Osmotic pressure is the pressure that develops in a system due to osmosis.
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Osmosis Demonstration
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4.2 Permeability of the Plasma Membrane
Osmosis Isotonic: the solute concentration is equal inside and outside of a cell Hypotonic: a solution has a lower solute concentration than the inside of a cell Hypertonic: a solution has a higher solute concentration than the inside of a cell
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Osmosis in Animal and Plant Cells
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4.2 Permeability of the Plasma Membrane
Transport by Carrier Proteins Carrier proteins combine with a molecule or ion to be transported across the membrane. Carrier proteins are required for: Facilitated Transport Active Transport
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Facilitated Transport
Small molecules that are not lipid-soluble Molecules combine with carrier proteins Molecules follow the concentration gradient Energy is not required
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4.2 Permeability of the Plasma Membrane
Active Transport Small molecules Molecules combine with carrier proteins Molecules move against the concentration gradient Energy is required
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The Sodium-Potassium Pump
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4.2 Permeability of the Plasma Membrane
Vesicle Formation Transport of large molecules Requires energy Keeps the macromolecule contained
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4.2 Permeability of the Plasma Membrane
Vesicle Formation Exocytosis - Vesicles form as a way to transport molecules out of a cell
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Exocytosis
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Vesicle Formation Vesicle Formation
Endocytosis - Vesicles form as a way to transport molecules into a cell Phagocytosis: Large,particulate matter Pinocytosis: Liquids and small particles dissolved in liquid Receptor Mediated Endocytosis: A type of pinocytosis that involves a coated pit
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Three Methods of Endocytosis
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