Transcript Cell Transport

Moving through the
Plasma Membrane
What does a phospholipid look like?
Let’s Review
• What is homeostasis?
• What is the job of the plasma
membrane?
• How do you think the cell
membrane helps a cell maintain
homeostasis?
What does the
Plasma Membrane look like?
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Cholesterol
Inside Cell (Cytoplasm)
Phospholipids
The Plasma Membrane
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Cholesterol
Phospholipids
Inside Cell (Cytoplasm)
The Plasma Membrane
Polar
Non-Polar
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Phospholipids
Cholesterol
Inside Cell (Cytoplasm)
Plasma Membrane:
The Fluid Mosaic Model
Plasma Membrane:
The Fluid Mosaic Model
• Fluid because
–the phospholipid and protein
molecules are able to move
around. Not stuck in one place.
• Mosaic because
– the membrane contains a
variety of proteins embedded
with the phospholipids.
How do particles move
in and out of the cell?
Passive Transport
energy
• No additional _______________
is required because every
particle has its own energy
• This energy produces
random
________________
movement in
particles. (a.k.a Brownian
motion)
Diffusion
• Diffusion is the movement of
high
substances from a ________
concentration to a low
concentration.
• Diffusion is caused by
Brownian__________
Motion
__________
amount
• Concentration is the _________
area
of something in a given ______.
How does it work?
• Particles move down the
concentration gradient, until
equal
the concentration is _________
throughout an area.
• Then the system is said to
have reached dynamic
equilibrium.
A.
High Concentration
of Blue Dots
High Concentration of
Orange Dots
Low Concentration of
Orange Dots
Low Concentration of
Blue Dots
B.
System has reached dynamic equilibrium
Examples of diffusion at work
• Why does food smell fragrant
when cooked?
• Have you ever stood next to
someone wearing strong
perfume?
Permeability of a membrane
• Permeable: anything can pass
through
• Semi-permeable: some things
can pass through
• Impermeable: nothing can
pass through
Back to the plasma membrane…
Outside Cell (Extracellular Matrix)
Inside Cell (Cytoplasm)
• The plasma membrane is
described as semi-permeable
because some substances can
move through it:
–Small and
–Non-polar
Osmosis
• Diffusion of _________
water across
a membrane
• Water molecules can pass
through pores or openings
proteins in the
created by __________
plasma membrane .
Back to the plasma membrane…
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Cholesterol
Inside Cell (Cytoplasm)
Phospholipids
The Cell’s Environment:
Isotonic
• In an isotonic
environment the solute
concentrations are
equal
___________
and there is
no NET movement of
water.
The Cell’s Environment:
Hypotonic
• In a hypotonic
environment, there are
less
__________
solutes
outside than inside and
water moves into the
cell.
The Cell’s Environment:
Hypertonic
• In a hypertonic
environment there are
more solutes outside
_________
than inside and water
moves out of the cell.
Environment Water
Effect on
Effect on
outside cell moves… ANIMAL cell PLANT cell
Hypotonic
Hypertonic
Isotonic
Environment Water
Effect on
Effect on
outside cell moves… ANIMAL cell PLANT cell
Hypotonic
Hypertonic
Isotonic
In
Swells, then
bursts
(cytolysis)
Animal Cell Cytolysis
Cells burst
Cell still intact
Environment Water
Effect on
Effect on
outside cell moves… ANIMAL cell PLANT cell
Hypotonic
Hypertonic
Isotonic
In
Swells,
Swells,
then bursts increases
(cytolysis) turgor
pressure
Environment Water
Effect on
Effect on
outside cell moves… ANIMAL cell PLANT cell
Hypotonic
In
Hypertonic
Out
Isotonic
Swells,
Swells,
then bursts increases
(cytolysis) turgor
pressure
Environment Water
Effect on
Effect on
outside cell moves… ANIMAL cell PLANT cell
Hypotonic
In
Swells,
Swells,
then bursts increases
(cytolysis) turgor
pressure
Hypertonic
out
Shrinks
(crenation)
Isotonic
Environment Water
Effect on
outside cell moves… ANIMAL
cell
Hypotonic
In
Swells,
Effect on
PLANT cell
Hypertonic
Shrink
(plasmolysis)
Swells,
then bursts increases
(cytolysis) turgor
pressure
Isotonic
out
Shrinks
(crenation)
Environment
outside cell
Water
moves…
Effect on
Effect on
ANIMAL cell PLANT cell
Hypotonic
In
Swells, then Swells,
bursts
increased
(cytolysis) turgor
pressure
Hypertonic
Out
Shrinks
(crenation)
Isotonic
Shrinks,
(plasmolysis)
Environment Water
Effect on
outside cell moves… ANIMAL
cell
Hypotonic
In
Swells,
Effect on
PLANT cell
Hypertonic
Shrink
(plasmolysis)
Swells,
then bursts increases
(cytolysis) turgor
pressure
Isotonic
out
Shrinks
(crenation)
Plant cell: Plasmolysis
Plasmolyzed
Cells
Normal cells
Environment Water
Effect on
outside cell moves… ANIMAL
cell
Hypotonic
In
Swells,
Effect on
PLANT cell
Hypertonic
out
Shrink
(plasmolysis)
Isotonic
In and
out at
the same
rate
Swells,
then bursts increases
(cytolysis) turgor
pressure
Shrinks
(crenation)
Environment Water
Effect on
outside cell moves… ANIMAL
cell
Hypotonic
In
Swells,
Effect on
PLANT cell
Hypertonic
out
Shrink
(plasmolysis)
Isotonic
In and
Stays the
out at
same
the same
rate
Swells,
then bursts increases
(cytolysis) turgor
pressure
Shrinks
(crenation)
Environment Water
Effect on
outside cell moves… ANIMAL
cell
Hypotonic
In
Swells,
Effect on
PLANT cell
Hypertonic
out
Shrink
(plasmolysis)
Isotonic
In and
Stays the
out at
same
the same
rate
Swells,
then bursts increases
(cytolysis) turgor
pressure
Shrinks
(crenation)
Stays the
same
Osmosis in Action
• What happens when you
sprinkle salt on a slug?
• If you are stranded at sea and
run out of water, should you
drink sea water?
** Water moves from a hypo to a
hypertonic environment.
True or False
1. In diffusion, particles move from
an area of high to low
concentration.
2. Diffusion does not require any
additional energy to occur.
3. Small, charged or polar particles
can move through the cell
membrane by simple diffusion.
What if a cell needs large
or charged/ polar
molecules. Can they
move across the
membrane?
Yes!
Selectively Permeable Membrane
• The cell membrane “picks”
what molecules can enter
and exit the cell because
proteins in the membrane
allow specific
macromolecules or ions in
or out of the cell.
Facilitated diffusion
• Proteins help particles
move across the membrane
• Transport proteins span the
phospholipid bilayer, but
specific
allow only ___________
molecules through.
>> Selectivity
Types of transport proteins
Ion channels
• ____
__________ are non–polar on
the outside and polar on the
inside. They provide a pore for
ions and polar particles to move
through.
Carrier Proteins
• _________
_______________ bind
to specific particles, carry them
through the membrane, and
release them on the other side.
http://www.stolaf.edu/people/giannini/flashanimat/transport/caryprot.swf
Remember!
• In diffusion-particles (solutes)
move from an area of HIGH
concentration to LOW In
osmosis- water moves from a
HYPOTONIC environment to a
HYPERTONIC environment
• Diffusion requires NO energy
input
•
http://scienceguyinatie.blogspot.com/2008/11/cell-membrane-animation-of-word-wall.html
Simple vs. Facilitated
• In simple diffusion, particles
move between phospholipid
molecules of the membrane.
• In facilitated diffusion,
particles move through
transport proteins in the
membrane.
• Both do NOT use energy.
Particles must move down the
concentration gradient.
But what if you
needed to move
particles against their
concentration
gradient?
Active Transport
• Transport proteins use
________to
move particles
energy
against their concentration
gradient, from a low
concentration to a high
concentration.
Sodium-Potassium Pump:
• Carrier- protein that pumps
3 sodium ions (Na+)________
outside
the cell, while pumping 2
potassium ions (K+)________.
inside
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html
http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html
1. 3 Na+ ions from inside the cell bind
to the pump protein. Energy from
ATP is added to the protein.
2. The Na+ ions are moved to the
outside of the cell.
3. The 3 Na+ ions are released and 2
K+ ions bind to the protein.
4. The protein changes back and
releases the 2 K+ ions into the cell.
Vesicle Mediated Transport
• The fluid plasma membrane
can “pinch” off forming
vesicles that can move very
large
_______particles
or lots of
small
______particles.
• This process needs energy
_______.
Endocytosis
• Outside materials are
inside the cell.
brought __________
1) Food
particle
2) Pouch forming
around food
3) Vesicle
with food
Endocytosis
Phagocytosis
• “Cell eating”
• Cell engulfs large food particles
and the vesicle is a food vacuole.
•
http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/phagocitosis.swf
Pinocytosis
• “cell drinking”
• Cell engulfs small droplets of
surrounding fluid.
Exocytosis
• Material from inside the cell is
outside by vesicles.
released _________
1) Vesicle
fuses with
membrane
2) Pouch
opens
3) Particle
released