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? Outside Cell (Extracellular Matrix) Protein Glycoprotein Phospholipids Cholesterol 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?

Permeability 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 energy No additional _______________ is required because every particle has its own energy This energy produces ________________ movement in particles. (a.k.a Brownian motion) random

Diffusion area high Brownian Motion 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 ______. high Brownian Motion amount area

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

A. B. High Concentration of Orange Dots Low Concentration of Blue Dots High Concentration of Blue Dots Low Concentration of Orange Dots B. System has reached dynamic equilibrium

Back to the plasma membrane… Outside Cell (Extracellular Matrix) Inside Cell (Cytoplasm)

Osmosis Diffusion of _________ across a membrane Water molecules can pass through pores or openings created by __________ in the plasma membrane . water proteins

Back to the plasma membrane… Outside Cell (Extracellular Matrix) Protein Glycoprotein Phospholipids Cholesterol Inside Cell (Cytoplasm)

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 Cells burst Cell still intact

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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 Plasmolyzed Cells Normal cells

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

Swells, then bursts (cytolysis) Swells, increases turgor pressure 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

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 In diffusion, particles move from an area of high to low concentration. Diffusion does not require any additional energy to occur. Small, charged or polar particles can move through the cell membrane by simple diffusion.

What if a cell needs large or charged/ polar molecules 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 allow only ___________ molecules through. >> Selectivity specific

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 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://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

3 Na+ ions from inside the cell bind to the pump protein 3 Na+ ions from inside the cell bind to the pump protein. Energy from ATP is added to the protein. The Na+ ions are moved to the outside of the cell. The 3 Na+ ions are released and 2 K+ ions bind to the protein. 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 _______. large small energy

Endocytosis Outside materials are brought __________ the cell. inside 3) Vesicle with food 1) Food particle 2) Pouch forming around 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 released _________ by vesicles. outside 1) Vesicle fuses with membrane 3) Particle released 2) Pouch opens