Download CHAPTER 3 SECTION 2

CHAPTER 3 SECTION 2
MOVING CELLULAR MATERIALS
 PASSIVE TRANSPORT – CELL MEMBRANE CONTROLS WHAT ENTERS
AND LEAVES THE CELL - SELECTIVELY PERMEABLE
 PASSIVE TRANSPORT REQUIRES LITTLE ENERGY
3 TYPES OF PASSIVE TRANSPORT
 DIFFUSION – MOVEMENT OF MATERIALS FROM AN AREA OF HIGHER
CONCENTRATION TO AN AREA OF LOWER CONCENTRATION UNTIL
EQUILIBRIUM IS REACHED, AND DIFFUSION STOPS
 EXAMPLE – OXYGEN MOVES FROM HIGH LEVELS IN YOUR BLOOD
TO LOWER LEVELS IN CELLS THROUGHOUT YOUR BODY (BIG TOE)
OSMOSIS-THE DIFFUSION OF WATER
 WATER MOLECULES MOVE BY DIFFUSION INTO AND OUT OF CELLS
 DIFFUSION OF WATER THRU A CELL MEMBRANE IS OSMOSIS– (WO)
 WATER MOVES FROM AREA OF HIGH CONCENTRATION TO AN AREA
OF LOW CONCENTRATION
 IN A PLANT, IF CELLS LOSE TOO MUCH WATER, THE PLANT GOES
LIMP. IF CELLS ARE WATER FILLED, THE PLANT STANDS STRAIGHT
FACILITATED DIFFUSION
 SOME SUBSTANCES ARE TOO LARGE TO PASS THRU THE CELL
MEMBRANE ON THEIR OWN. THEY NEED HELP FROM TRANSPORT
PROTEINS.
 TRANSPORT PROTEINS HELP MOVE MATERIALS INTO AND OUT OF
THE CELL
ACTIVE TRANSPORT
 WHEN ENERGY IS NEEDED TO MOVE MATERIALS THRU A CELL
MEMBRANE
 THIS HAPPENS WHEN WE WANT TO MOVE SUBSTANCES FROM AN
AREA OF LOWER CONCENTRATION TO AN AREA OF HIGHER
CONCENTRATION
 INVOLVES TRANSPORT PROTEINS – PROTEIN BONDS TO MATERIAL
NEEDING ENTRY TO THE CELL. AFTER PROTEIN ENTERS THE CELL,
IT RELEASES THE ATTACHED SUBSTANCE AND HELPS ANOTHER
THRU THE MEMBRANE
ENDOCYTOSIS AND EXOCYTOSIS
 SOME LARGE MOLECULES CAN’T USE TRANSPORT PROTEINS OR
DIFFUSION TO ENTER A CELL
 LARGE MOLECULES CAN ENTER THE CELL WHEN THEY ARE
SURROUNDED BY THE CELL MEMBRANE
 MEMBRANE FOLDS AROUND THE SUBSTANCE, ENCLOSING IT
IN A SPHERE SHAPED VESSICLE – TRANSPORT AND STORAGE
STRUCTURE
 THE SPHERE PINCHES OFF AND THE VESICLE ENTERS THE
CELL’S CYTOPLASM
 ENDOCYTOSIS – WHEN CELL MEMBRANE SURROUNDS A
SUBSTANCE AND IT ENTERS THE CELL
 EXOCYTOSIS – OPPOSITE OF ENDOCYTOSIS
 MATERIAL LEAVING CELL IS SURROUNDED BY
MEMBRANE (SPHERE), THE SPHERE FUSES WITH CELL
MEMBRANE AND THEN OPENS UP TO RELEASE
MATERIALS FROM THE CELL