Do Now 11.19
OBJECTIVES:1. Identify three ways that active transport is
different from passive transport. 2. Define endocytosis and
exocytosis. 3. Describe the function of the sodium-potassium
pump as an example of active transport.
TASK: One curve represents the diffusion of
glucose through the lipid bilayer, and the other
represents the transport of glucose by facilitated
diffusion. Which curve corresponds to
facilitated diffusion? Explain your reasoning.
TASK2:
Syllabus update:
Switch today (11/19)
and tomorrow (11/20)
Definition:
Passive Transport
Type 1
Type 2
Type 3
DIFFUSION
Definition: Key Term:
Solute
molecules
move from
an area of
high
concentration to an
area of low
conc.
Powered
by the
random
motion of
molecules.
Equilibrium
OSMOSIS
Hypertonic:
Solute conc. Bigr
outside. H2O out
Isotonic:
Solute conc. =
Inside & out.
No net H2O
change.
Hypotonic:
Solute conc. Lower outside.
H2O in. Hypo-Hippo
The process of
substances passing
through the cell
membrane WITHOUT
ANY INPUT OF
ENERGY BY THE
CELL.
FACILITATED
DIFFUSION
Definition:
Definition:
Diffusion of
water from
an area of
high H2O
conc. (low
solute
conc.) to
low (high
solute
conc.)
Required for
Ions
(charged
molecules)
And
Large
Molecules
Cell uses
carrier
proteins in
membrane to
allow the
diffusion of
molecules
that can’t
pass through
membrane
alone.
Active Transport
• Active transport processes are different
from passive ones:
– Energy is required.
– Substances move UP their concentration
gradients from lower conc. to higher.
– Equilibrium is PREVENTED.
Endocytosis
• “Endo-” means in.
• “cyto-” means cell.
• “osis” means process of.
• What does endocytosis mean?
• Endocytosis: the process by which cells take in
large amounts of material, by folding in the cell
membrane
Endocytosis
Example
• Pinocytosis:
non-specific
endocytosis
of small
amounts of
extracellular
fluid.
• Greek:
“pino-” =
“drinking”
Endocytosis
Example
• Phagocytosis:
the endocytosis of
solid particles
such as bacteria,
cell debris, or
other solids
• Greek: “phago-”
= “eating”
Phagocytes
• Phagocytes,
such as some
types of white
blood cells,
engulf foreign
cells by
phagocytosis.
For Protists, Phagocytosis = Eating
Exocytosis
• Exocytosis is the same process as endocytosis,
except in reverse.
• The stuff leaving may be:
– Proteins released into the ECF
– New lipids for expanding the membrane
– Membrane proteins
– Chemicals for communication, etc. (e.g. dopamine)
Exocytosis
Endo and Exocytosis – quick review
The Sodium / Potassium Pump
• The Na+/K+ pump is responsible for
maintaining the electrical charge of a cell
– Cells are negative
• Communication, e.g. neurons
• Cation uptake
• It is an example of a membrane pump which
move specific things into or out of the cell
AGAINST THEIR CONCENTRATION
GRADIENT.
• Since it requires energy, it is an example of
ACTIVE TRANSPORT!
How the
Na+/K+
Pump
Works
• Don’t forget the animation….
Na+/K+ Pump… Drake
demonstrates…
Recap: Active Transport Uses ATP
• Active transport is different from passive in 3
key ways (energy, up gradient, no equilibrium)
• Endocytosis = cell taking in material by infolding
the membrane.
– Pinocytosis = “cell drinking” ECF
– Phagocytosis = “cell eating” bacteria, etc.
• Exocytosis = cell exporting materials in bulk.
• Na+/K+ Pump =
– an example of a membrane pump
– moves 3 Na+ out and 2 K+ in per cycle.
– Causes cells to be negatively charged.