Molecular Movement

Diffusion Movement of molecules from an area of high concentration to an area of low concentration Molecules never stop moving Molecules always try to create equal concentrations!

Concentration Gradient The gradual decrease from a high concentration to a low concentration Molecules are said to move DOWN a concentration gradient

Why? If no energy is used, everything moves from an organized state to a disorganized state Organisms use energy to maintain an organized state Ex. Your bedroom

Osmosis The movement of water from an area of greater concentration to an area of less concentration

Osmosis

What happens if... H 2 O concentrationEffect Greater outside the cell Water rushes into the cell Internal pressure increases Cell swells & bursts Greater inside the cell Water leaks out of the cell Cell shrinks

More water outside than inside Water equal on both sides More water inside than outside

Animal Cell

Isotonic Water concentration is equal on both sides of the cell

Hypotonic Internal water concentration is lower than the external water concentration Water rushes into the cell –Causes it to lyse (burst)

Hypertonic Internal water concentration is greater than the external water concentration Water rushes out of the cell –Causes it to shrivel

Animal CellPlant Cell HypotonicSwells and Lyses (Bursts) Turgid Normal IsotonicNormalFlagid, Limp HypertonicShriveledPlasmolized

Vacuole Water-filled compartment found in plant cells Exerts osmotic pressure on cells contents –Presses cell membrane tightly against cell wall –Pressure gives plants structures (leaves) firmness

Transport Systems 1.Passive Transport 2.Active Transport

Passive Transport Proteins move large molecules and molecules with electrical charges DOWN a concentration gradient NO CELLULAR ENERGY REQUIRED!

Active Transport Proteins move molecules UP a concentration gradient Uses ENERGY Ex. Soil w/low amounts of elements –Active Transport allows the roots to accumulate necessary elements

Transport Systems

It goes back to Organization! Systems attempt to remain organized Must put forth ENERGY! Entropythe tendency toward disorder, in a system (see slide 6)