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ATP – Adenosine Triphosphate
- cell ‘s energy source.
- When phosphates break off, gives off energy
for cell to use.
Active Transport
 Remember in passive transport, molecules
move with the concentration gradient (from
area of high [] to an area of low [] until they
reach equillibrium.
 Sometimes the cell needs more than just an
equal amount inside as outside
 Energy is used to pump molecules against the []
gradient
 Energy = ATP
Example: digestion
 Food is eaten to obtain nutrients.
 Small intestine moves nutrients across its
membrane and into the blood stream.
 Ex. Glucose – pumped across cell membrane
using a carrier protein. ATP activates the
protein to move glucose into the cell even
though the concentration outside the cell is
lower.
Ex. Nerve and muscle cells
 sodium-potassium pump.
 Sodium and potassium are what allow
messages to be sent between nerves.
 Messages = movement and function
Bulk Transport
 Large amounts of material moving into or out
of cell.
 Requires energy (ATP)
 Types:
 Endocytosis- movement of material into cell
 Phagocytosis : solids moving into cell
 Pinocytosis: liquids moving into cell
Phagocytosis
 Solid particle comes into contact with cell
membrane.
 Cell membrane moves around particle using
pseudopods (“false feet”) and engulfs (swallows)
particle.
pseudopod
Phagocytosis
 Once inside the cell, a lysosome fuses to the
particle and uses its digestive enzymes to
break down the particle.
http://en.wikipedia.org/wiki/File:Phagocytosis2.png
Phagocytosis
 White blood
cell
(macrophage)
engulfing
foreign bodies
in blood.
http://www.peterjurek.com/rbv_site/web_pages/phagocytosis.html
Exocytosis
 Reverse of endocytosis
 Movement of large particles out of the cell.
 Fig. 9 p. 71 of text
http://www.cdli.ca/courses/biol2201
/unit01_org04_ilo01/b_activity.html
Exocytosis
Nerve cell transmission
Activity at an axon terminal:
Neuron A is transmitting a signal
at the axon terminal to neuron B
(receiving). Features: 1.
Mitochondrion. 2. synaptic
vesicle with neurotransmitters.
3. Autoreceptor. 4. Synapse with
neurotransmitter released
(serotonin). 5. Postsynaptic
receptors activated by
neurotransmitter (induction of a
postsynaptic potential). 6.
Calcium channel. 7. Exocytosis
of a vesicle. 8. Recaptured
neurotransmitter.
http://www.thefullwiki.org/Axon_terminal