moving through the plasma membrane. let’s review what is homeostasis? what is the job of the...
TRANSCRIPT
Moving Through the Plasma Membrane
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?
Structure and Function
• Phospholipid bilayer with carbohydrates and proteins imbedded into itself
• Brings in essential materials and excretes waste products
What does a phospholipid look like?
Polar head/ hydrophilic
Nonpolar head/ hydrophilic
What does the Plasma Membrane look like?
GlycoproteinProtein
CholesterolPhospholipids
Outside Cell (Extracellular Matrix)
Inside Cell (Cytoplasm)
The Plasma Membrane
Glycoprotein
Protein
CholesterolPhospholipids
Outside Cell (Extracellular Matrix)
Inside Cell (Cytoplasm)
Non-Polar Polar
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.
Plasma Membrane:The Fluid Mosaic Model
How do particles move in and out of the cell?
Permeability of a membranePermeability of a membrane
• Permeable: anything can pass through
• Semi-permeable: some things can pass through
• Impermeable: nothing can pass through
• The plasma membrane is described as semi-permeable because some substances can move through it:–Small and–Non-polar
Passive Transport• No additional _______________ is
required because every particle has its own energy
• This energy produces ________________ movement in particles. (a.k.a Brownian motion)
energy
random
Diffusion• Diffusion is the movement of
substances from a ________ concentration to a low concentration.
• Diffusion is caused by ______________________
• Concentration is the _________ of something in a given ______.
Brownian Motion
high
amountarea
Examples of diffusion at work
• Why does food smell fragrant when cooked?
• Have you ever stood next to someone wearing strong perfume?
How does it work?
• Particles move down the concentration gradient, until the concentration is _________ throughout an area.
• Then the system is said to have reached dynamic equilibrium.
equal
High Concentration of Blue Dots
Low Concentration of Orange Dots
High Concentration of Orange Dots
Low Concentration of Blue Dots
System has reached dynamic equilibrium
A.
B.
Outside Cell (Extracellular Matrix)
Inside Cell (Cytoplasm)
Back to the plasma membrane…
Osmosis
• Diffusion of _________ across a membrane
• Water molecules can pass through pores or openings created by __________ in the plasma membrane .
water
proteins
Glycoprotein
Protein
Cholesterol Phospholipids
Outside Cell (Extracellular Matrix)
Inside Cell (Cytoplasm)
Back to the plasma membrane…
The Cell’s Environment: Isotonic
• In an isotonic environment the solute concentrations are ___________ and there is no NET movement of water.
equal
The Cell’s Environment: Hypotonic
• In a hypotonic environment, there are __________ solutes outside than inside and water moves into the cell.
less
The Cell’s Environment: Hypertonic
• In a hypertonic environment there are _________ solutes outside than inside and water moves out of the cell.
more
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic
Hypertonic
Isotonic
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Hypertonic
Isotonic
Animal Cell Cytolysis
Cell still intact
Cells burst
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
Isotonic
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic Out
Isotonic
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic out Shrinks (crenation)
Isotonic
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic out Shrinks (crenation)
Shrink (plasmolysis)
Isotonic
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increased turgor pressure
Hypertonic Out Shrinks
(crenation)
Shrinks, (plasmolysis)
Isotonic
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic out Shrinks (crenation)
Shrink (plasmolysis)
Isotonic
Plant cell: Plasmolysis
Normal cells
Plasmolyzed Cells
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic out Shrinks (crenation)
Shrink (plasmolysis)
Isotonic In and out at the same rate
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic out Shrinks (crenation)
Shrink (plasmolysis)
Isotonic In and out at the same rate
Stays the same
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic out Shrinks (crenation)
Shrink (plasmolysis)
Isotonic In and out at the same rate
Stays the same
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 False1. 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 MembraneSelectively 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 allow only ___________ molecules through. >> Selectivity
specific
Types of transport proteins• ____ __________ are non–polar on the
outside and polar on the inside. They provide a pore for ions and polar particles to move through.
Ion channels
• _________ _______________ 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
Carrier Proteins
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 against their concentration gradient, from a low concentration to a high concentration.
energy
Sodium-Potassium Pump:
• Carrier- protein that pumps 3
sodium ions (Na+)________
the cell, while pumping 2
potassium ions (K+)________.
outside
inside
http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.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 _______particles or lots of ______particles.
• This process needs _______.
largesmall
energy
Endocytosis• Outside materials are brought
__________ the cell. 1) Food particle
3) Vesicle with food
2) Pouch forming around food
inside
EndocytosisPhagocytosis• “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
released _________ by vesicles.
1) Vesicle fuses with membrane
2) Pouch opens
3) Particle released
outside