Transcript Active Transport

Active Transport
pp. 67 to 71
• We know that passive transport involves NO
energy, but....
• As living beings, we NEED energy to sustain life
processes. We eat food containing nutrients for
energy, glucose being one of them.
– Recall: glucose cannot be sustained inside body as it is
soluble, so it must be converted into glycogen to get
energy “stores”
– This conversion MAKES energy in the form of
adenosine triphosphate (ATP) = source of energy for
cells
– ATP reacts with certain compounds to release energy
to drive life processes
Active Transport – 3 Types
Active
Transport
Cell
Membrane
Carrier
Protein
Endocytosis
Exocytosis
1. CM Carrier Protein
• Bit similar to facilitated diffusion, but…
• Cell energy (ATP) is used to move substance
across CM against concentration gradient
(low  high)
– Remember, simple diffusion is the movement of
substances using no energy to maintain equal
concentrations on both sides (high  low = equal)
1. Substance (eg. protein,
vitamin, molecule)
binds to carrier protein.
2. Carrier protein uses
energy (ATP) to flip over
& “pumps” (releases)
substance to other side
of the membrane.
3. Carrier protein flips
back to get another
substance.
HIGH CONCENTRATION
DIFFUSION
LOW CONCENTRATION
Bulk Transport
• Diffusion and CM carrier proteins move small
amounts of molecules, sometimes ONE molecule
at a time. It works but may not be the most
efficient.
• Cells need to move large amounts of materials
(bulk) in or out of the cell, all at once = bulk
transport
• Involves energy (ATP)
• Two kinds of bulk transport: endocytosis and
exocytosis
2. Endocytosis
• A type of bulk transport that is used to bring
large amounts of material INTO the cell.
• There are 2 kinds:
– Phagocytotis: bulk transport of solids
– Pinocytosis: bulk transport of liquids
Phagocytosis: (cell eating)
• large particles, whole cells
or solids enter the cell
• Pseudopods (sin:
pseudopodium) enclose
food
• enter as a food vacuole
Pinocytosis: (cell drinking)
• bulk transport of
dissolved solutes or fluids
into the cell
• enter as a vesicle
Exocytosis
• A type of bulk transport that is move large
amounts of material OUT of the cell.
• Materials are encased in secretory vesicles (in
case of proteins, vesicles form at the end of the
Golgi appartus and breaks off)
• The vesicle move towards CM. Vesicle fuses
with CM and expels content to extracellular
fluids.