TB - p 90- 91
WB - p 150-151
ACTIVE TRANSPORT
Learning intentions:
To define active transport
To identify types of active
transport
Active Transport
Why is it ‘Active’?
• Energy (ATP) required
ATP is short for Adenosine tri phosphate
• ATP is considered by biologists to be the energy currency of life.
• It is the high-energy molecule that stores the energy we need to do just
about everything we do.
• It is present in the cytoplasm of every cell, and essentially all the
physiological mechanisms that require energy to work obtain it directly
from the stored ATP.
• As food in the cell is used up, the released energy is used to re-form the
ATP molecule so that the cell always maintains a supply of this essential
molecule
Active transport is
• The movement of substances from an area of low
concentration to an area of high concentration.
Ie Against
the
concentration gradient
http://www.youtube
.com/watch?v=STz
OiRqzzL4&NR=1
Three types of Active Transport
1. Endocytosis
2. Exocytosis
3. Ion Pumps
Look these terms up in your TB and write down their
definitions
Endocytosis
• Movement into the cell
(enter)
• Phagocytosis – “cell eating”
A food vacuole is formed
• Pinocytosis – “cell drinking”
A Fluid vesicle is formed
• E.g. An Amoeba drinking
• Animation of endocytosis
Cytosis: movement of large molecules
through the cell membrane; requires ATP
Exocytosis
Cytosis: movement of large molecules
through the cell membrane; requires ATP
• Movement out of the cell (exit)
• Vesicles bud off from golgi
apparatus or ER, vacuole fuses
with cell membrane and expels
contents
• Secretions e.g. digestive enzymes
released, glands
• Animation of exocytosis
Vacuole
• Exocytosis
• Or
• Endocytosis?
Do WB p151
TB - p 90- 91
WB - p 150-151
ACTIVE TRANSPORT (2)
Learning intentions:
To define ion pump
transport
To identify types of ion
pumps
Ion Pumps (WB150)
Ion: a charged particle
• Proteins in the cell membrane can actively accumulate
specific ions on one side of the membrane to control the
amount
• Animation of an ion pump
Example 1 –Proton Pump
A protein is pumping
Hydrogen Ions (protons).
It is a proton pump.
14
Active transport model
animation
Example 2 –
Sodium Potassium
Pump
Example 3 - Cotransport
When water is pumped uphill, the energy it creates as it moves freely
downhill can be used. The same occurs in cells – Co transport
1. A molecules is
first pumped
against its
concentration
gradient
2. It then diffuses
back
3. The energy
created by its
diffusion is
used to pump
another
molecule
against its
concentration
gradient
1.
2
3.
Do page 150 in WB