Download Active Transport

Active Transport
Active Transport
• Requires energy
– in the form of ATP (useful cellular energy)
– movement against the concentration gradient
What does
“against” the
concentration
gradient
mean??
2 methods of Active Transport
1. Pumps
2. Change in the cell membrane (aka vesicular transport)
Active Transport Pumps:
• Requires a protein channel called a “pump”
• Requires ATP
• Movement from low concentration to high
concentration
– moving up the hill
hi concentration
low concentration
• Works in the opposite direction of facilitated
diffusion.
Active transport pump
• Energy (by way
of ATP) forces
materials
through a
protein in the
membrane
against
concentration
gradient.
You do not need to
understand HOW
this works…just
WHY a cell would
require energy in
order to do this.

Why Pump?
• Nerve cells need a difference
in ions (charge) on either
side of the membrane so
they can fire.
Which way would the
potassium ions (K+)
tend to go?
(Would they go into
the cell or out of the
cell? How do you
know?)
Change in cell membrane
(2nd type of active transport process)
• A.K.A. “Vesicular Transport” - Used for large
substances or large amounts of substances.
• Two types:
– Endocytosis:
• IN to the cell (ENTER)
– Exocytosis:
• OUT of the cell (EXIT)
Change in cell membrane
(2nd type of active transport process)
• Endocytosis (IN)
– Takes in (engulfs) large material
• Cell membrane moves in until it encapsulates material,
becoming a vesicle.
Endocytosis: (IN)
–Two types:
• Phagocytosis
• Pinocytosis
Phagocytosis:
• “Cell Eating”
– Pseudopods engulf material with
extensions of the cell
membrane.
– E.g. White blood cell taking in
foreign material for destruction.
– E.g. Amoeba engulfing a diatom
Phagocytosis:
Pinocytosis:
• “Cell Drinking”
– Membrane wraps
around a big drop of
solution (solute &
solvent) and pulls it in.
Pinocytosis:
Change in cell membrane
(2nd type of active transport process)
• Exocytosis (OUT)
– Vesicle that gets rid of large
material
• Vesicle fuses with cell
membrane, releasing
contents to outside of cell.
– E.g. Waste
– E.g. Digestive enzymes
A goblet cell procedures mucin
which when dissolved in water
is the main component of
mucus. What is the purpose of
mucus?
Exocytosis: (OUT)
RNA
Rough ER
Golgi apparatus
Protein in vesicle
Plasma membrane
Figure 7.14 The formation and functions of lysosomes (Layer 1)
Figure 7.14 The formation and functions of lysosomes (Layer 2)
Figure 7.14 The formation and functions of lysosomes (Layer 3)
Often
used to
recycle
cell parts
(do NOT need
to know for
test)