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)

Fluid-mosaic Model of Plasma Membrane Structure

4.1 Plasma Membrane Structure and Function Types of Membrane Proteins Channel Proteins Carrier Proteins Cell Recognition Proteins Receptor Proteins Enzymatic

A Proteins

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

How Molecules Cross the Plasma Membrane

Passage of Molecules into and out of the Cell Know for test

4.2 Permeability of the Plasma Membrane Diffusion and Osmosis Diffusion is the movement of molecules from an area of higher to lower concentration

Process of Diffusion

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

Gas Exchange in Lungs

4.2 Permeability of the Plasma Membrane Osmosis Osmosis is the diffusion of water across a differentially permeable membrane.

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.

Osmosis Demonstration

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

Osmosis in Animal and Plant Cells

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

Facilitated Transport Small molecules that are not lipid-soluble Molecules combine with carrier proteins Molecules follow the concentration gradient Energy is not required

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

The Sodium-Potassium Pump

4.2 Permeability of the Plasma Membrane Vesicle Formation Transport of large molecules Requires energy Keeps the macromolecule contained

4.2 Permeability of the Plasma Membrane Vesicle Formation Exocytosis - Vesicles form as a way to transport molecules out of a cell

Exocytosis

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

Three Methods of Endocytosis