Lab 4: How things move

Brownian Movement

• the driving force for all forms of passive transport

• the random movement of molecules due to kinetic energy

• Temperature affects the rate; the higher the temperature, the greater the kinetic energy

Diffusion

• the movement of any substance from a region of high concentration to a region of low concentration

Concentration Gradient

• difference in the concentration of molecules between both sides of the membrane

• provides the driving force for the diffusion molecules

• the rate of diffusion is dependent on several factors; temperature, the molecular weight of the molecules being transported. and the concentration of the particles that are diffusing

Dynamic Equilibrium

• no net movement of molecules occurs

• the particles are still moving, however, an equal number of particles are moving in either direction

Osmosis

• the movement of water from a region of high water concentration to a region of low water concentration through selective permeable membrane.

Passive transport

• does not require energy to move molecules across the membrane because the molecules are moving from an area of high concentration to an area of low concentration, down the concentration gradient

Simple Diffusion

• the movement of molecules directly through the membrane

Facilitated Diffusion

• the movement of molecules down their concentration gradient through a membrane protein

Dialysis

• separation of dissolved solids by means of a selectively permeable membrane

Active Transport

• the movement of molecules against the concentration gradient through a specialized membrane protein using energy

What is found in plant cells but not animal cells ?

• Elodea

• the cell wall & the chloroplast

Plasmolysis

• the shrinkage of the cell membrane away from the cell wall

• due to water loss when the cell is placed into a hyperosmotic solution

Osmosis

• the movement of water from a region of low water concentration through the semi-permeable membrane

• in plant cells, water loss by osmosis is accompanied by a decrease in the turgor pressure within the cell