Transport of Materials

TRANSPORT OF MATERIALS

Passive Transport

PASSIVE TRANSPORT Movement of materials that does not require

energy from the cell.

Cell membranes are selectively permeable Allows only certain materials to pass through

Particles move across a concentration gradient Move from an area of high concentration to an

area of low concentration.

SIMPLE DIFFUSION Movement of small particles directly through

the plasma membrane

Speed of diffusion depends on Temperature

Faster at higher temperatures Difference in concentrations

Faster with greater difference

Molecules move until dynamic equilibrium is reached State of balance where particles are equal in

concentration in all directions.

FACILITATED DIFFUSION Movement of larger molecules or charged

ions through protein channels Ions are molecules in which the total number of

electrons is not equal to the total number of protons, giving it a net positive or negative charge.

Essential chemicals travel this way glucose, sodium ions, chloride ions

FACILITATED DIFFUSION – CONT’D Pore proteins

Allows passage of small ions across concentration gradient

Carrier Proteins Special protein

gates openand closeto allow passage.

OSMOSIS Diffusion of water

Semi-permeable membrane prevents movement of solute molecules

Water molecules move to even out the concentrations

OSMOSIS CONT’D Osmosis occurs whenever there is a solute

concentration difference

Special terms used to compare solutions Isotonic - two solutions with the same solute

concentration Hypertonic – a solution with a higher solute

concentration Hypotonic – a solution with a lower solute

concentration.

OSMOSIS – CONT’D What happens to cells placed in solutions?

Animal cells

Plant cells