1. ACTIVE TRANSPORT
Cell Membrane Pumps
Endocytosis
Exocytosis

2. ACTIVE
TRANSPORT
 In many cases, cells must move molecules UP
against their concentration gradient.
 Moving materials from areas of LOW concentration
to areas of HIGH concentration requires ENERGY.
 Cells must expend energy (ATP) to transport the
materials UP their concentration gradient.

3. CELL MEMBRANE PUMPS
 Carrier proteins not only assist in passive
transport (helping move specific molecules DOWN
their concentration gradients through facilitated
diffusion)but also help with some types of active
transport.
 Carrier proteins that serve in active transport are
called cell membrane pumps because they move
substances UP their concentration gradients.

4. HOW CELL MEMBRANE PUMPS WORK
 1. Carrier Protein (pump) binds to a specific kind of
molecules on one side of the cell membrane (where
the concentration is LOW).
 2. Protein (pump) changes shape, shielding
molecules for the hydrophobic interior of the lipid
bilayer.
 3. Protein (pump) then transports (moves) the
molecule across the membrane and releases it on
the other side (where the concentration is HIGH).
 4. Energy (ATP) is required to operate the pump.

5. CELL MEMBRANE PUMP VIDEO
http://www.youtube.com/watch?v=GTHWig1vOnY&feat
ure=related

6. ACTIVE TRANSPORT
 Macromolecules and food particles are too large to
pass through the cell membrane by the transport
processes we have studied so far.
 Any ideas on how to get those into the cell?
 How did you get the candy into your bag without
breaking any of the rules?

7. ENDOCYTOSIS (IT TAKES ENERGY!!!!)
 Process by which cells ingest external fluid,
macromolecules, and large particles (including
other cells!).
 The external materials are enclosed by a portion of
the cell, which folds into itself and forms a pouch.
 The pouch pinches off from the cell membrane
and becomes a membrane-bound organelle called
a vesicle that will later fuse with lysosomes or other
membrane-bound organelles.

8. TWO TYPES OF ENDOCYTOSIS
 Biologists distinguish two types of endocytosis, based
on the kind of material that is taken into the cell.
 Pinocytosis involves the transport of solutes or fluids.
(cell drinking)
 Phagocytosis is the ingestion of large particles or whole
cells. (cell eating)
 How would this be useful?
 Unicellular organisms feed by phagocytosis.
 Certain animal cells use phagocytosis to ingest bacteria
and viruses that invade the cell (we call cells that do this
phagocytes). Lysosome fuse with the vesicle formed to
destroy the bacteria or virus before it can harm the
animal.

10. EXOCYTOSIS (IT TAKES ENERGY!!!!)
 Exocytosis is endocytosis in reverse.
 Vesicles in the cytoplasm fuse with the cell
membrane then release their contents into the cell’s
external environment.
 Cells may use exocytosis to release large
molecules like proteins.
 Which organelle would have made the protein?
 Which organelle would have packaged it in a
vesicle to get it ready to ship?

11. EXOCYTOSIS

12. ENDOCYTOSIS VIDEO
 http://dvc.infohio.org/index.php?option=com_conten
t&view=article&id=11&Itemid=14&videoid=12082