Bellringer List the two things that make up the cell membrane. What does it mean to be selectively permeable?

From the lab, Order of the items… Biggest: ? Smallest: ? Where do the pores fit in?

Sizes of Molecules… Water (H2O) Iodine (I2K) Glucose (C6H12O6) Food Coloring (~450 atoms) Starch (~1000 atoms) So…how big are the pores of the membrane? Make an estimate (with an explanation) on the back side of your questions!!!

Fluid Mosaic Model http://www.susanahalpine.com/anim/Life/memb.htm http://www.youtube.com/watch?v=ULR79TiUj80

Role of the membrane? Selective permeability

Roles of the membrane proteins Move stuff across the membrane that can’t get across on its own Recognition – like nametags Receptors – trigger cellular responses Enzymes

How does the membrane regulate movement of molecules? It’s structure dictates!!

Cell Transport

Cell Membrane Cell Membrane Animation Made of phospholipids and proteins Molecules move into and out of a cell through the cell membrane The cell membrane is selectively permeable How certain molecules move through the cell is called cell transport Passive Transport Active Transport

Questions What happens when you spray air freshener or perfume? What happens when you put food coloring in water? THIS IS DIFFUSION!!!! Diffusion is also one way things are transported across the cell membrane

What is concentration? Amount of solute in a certain amount of solvent…think about kool-aid… Solvent – what does the dissolving (liquid) Solute – what is dissolved in the solvent Which is more concentrated?

Passive Transport Particles move from high concentration to low concentration Does NOT require extra cell energy Includes simple diffusion, osmosis, facilitated diffusion

SIMPLE DIFFUSION Movement of molecules from areas of high concentration to areas of low concentration Does not require energy (PASSIVE) Because molecules are in constant, random, motion! Will diffuse until reaches equilibrium (equal concentrations) Dynamic equilibrium (still moving!)

Diffusion Dynamic Equilibrium

For lab… To the beaker, add: Water Iodine To the tube, add: Glucose solution Starch To the beaker, add: Water Iodine

Make a hypothesis…. Will the glucose move? Which way? Why or why not? Will the iodine move? Which way? Why or why not? Will the starch move? Which way? Why or why not?

Flea Diffusion Analogy

Flea Diffusion Analogy

Flea Diffusion Analogy

Dynamic Equilibrium

Simple Diffusion in Cells Diffusion Animation Diffusion Across a Membrane

PROBLEM BREAK

OSMOSIS The diffusion of water across a membrane from an area of high concentration to low concentration No energy required (PASSIVE TRANSPORT) Occurs until reaches DYNAMIC EQUILIBRIUM Equal concentrations on both sides of the membrane

Tonicity of solutions Used to compare the relative concentrations Hypertonic solution with a higher concentration of solute So lower water concentration Hypotonic solution with a lower concentration of solute So higher water concentration Isotonic solutions with equal concentrations of solute Water diffuses from hypotonic solutions to hypertonic solutions!

http://www.linkpublishing.com/video-transport.htm#Brownian_Movement What About Cells?

Cells in Hypertonic Solution Water moves out of the cell Cell shrivels Low Hi

Hypotonic Solution Water moves into the cell Cell swells HYPOTONIC Animal cell – can burst Plant cell – builds up pressure on cell wall, but rigid cell wall keeps it from bursting HYPOTONIC Hi Lo

Isotonic Solution Water moves in and out of the cell Cell stays the same size Dynamic Equilibrium ISOTONIC

Osmosis Animations http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

What happens to slugs in salt? Dead bodies in the river?

FRAYER MODEL BREAK! Draw example define Passive transport Explain your example Does it require energy? Examples

Starter Consider the following information: Water, oxygen, and CO2 all readily move across a membrane Glucose, proteins and small ions (like Na+ or Cl-) cannot pass on their own Considering this information, devise a rule that describes what CAN and CANNOT pass through the membrane via SIMPLE DIFFUSION

Pumping Water Some organisms have vacuoles that pump out excess water that enters the cell Too much water in the cell = vacuole works hard pumping out water! http://www.linkpublishing.com/video-transport.htm#Brownian_Movement

FACILITATED DIFFUSION Particles move from high concentration to low concentration No energy needed (PASSIVE) Cells use proteins to “help” Transport Proteins Channel proteins http://www.stolaf.edu/people/giannini/biological%20anamations.html

Facilitated Diffusion FRAYER MODEL BREAK! Draw example define Facilitated Diffusion Explain your example Does it require energy?

Review passive transport

Active Transport Particles move from low concentration to high concentration (against the concentration gradient) DOES REQUIRE ENERGY!! Requires transport proteins Includes pumps, endocytosis, exocytosis, etc.

The sodium-potassium pump Active Transport = requires energy! Sodium is pumped out Potassium is pumped in Animation

Active transport Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients. Called Na+-K+ Pump

Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential

Pumps Some animals use salt pumps to maintain a constant concentration of salt in their bodies This requires energy! ACTIVE TRANSPORT!

Pom-Pom Potential Modeling passive and active transport along a cell membrane in a NERVE CELL What do nerves do? How do they do it?

Questions How did this activity model passive transport? How did this activity model active transport? Why do the membranes “work” to keep the charges on either side of the membrane “balanced”?

FRAYER MODEL BREAK! Draw example define Active transport Explain your example Does it require energy? Examples

VENN DIAGRAM TIME: MUWAHAHAHAHA ACTIVE TRANSPORT FACILITATED DIFFUSION

Moving the big stuff…

Exocytosis Large substances leave the cell Vesicle fuses with cell membrane and dumps contents

Exocytosis The opposite of endocytosis is exocytosis Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment

Exocytosis- moving things out. Moving the “Big Stuff” Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many hormones are secreted and how nerve cells communicate with one another.

Exocytosis Exocytic vesicle immediately after fusion with plasma membrane.

Ponder for a moment… How does exocytosis fit into PROTEIN SYNTHESIS????

Endocytosis Large substances enter the cell Cell membrane forms a “pit” and wraps around substance Cell membrane pinches off – forms a vesicle

Endocytosis

Cell Signaling Signaling activity Modeling Nerves…

Go to picture  http://learn.genetics.utah.edu/content/addiction/drugs/mouse.html

Journal Draw a diagram of what we just did and… Identify the types of transport going on, as completely as possible (there are TWO you should identify!). Provide justification for your selection.