Bellringer

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Bellringer

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

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From the lab, Order of the items

• Biggest ?
• Smallest ?
• Where do the pores fit in?

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Sizes of Molecules

• Water (H2O)
• Iodine (I2K)
• Glucose (C6H12O6)
• Food Coloring (450 atoms)
• Starch (1000 atoms)

Sohow big are the pores of the membrane? Make
an estimate (with an explanation) on the back
side of your questions!!!
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Fluid Mosaic Model

• http//www.susanahalpine.com/anim/Life/memb.htm
• http//www.youtube.com/watch?vULR79TiUj80

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Role of the membrane?

• Selective permeability

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Roles of the membrane proteins

• Move stuff across the membrane that cant get
  across on its own
• Recognition like nametags
• Receptors trigger cellular responses
• Enzymes

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How does the membrane regulate movement of
molecules?

• Its structure dictates!!

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Cell Transport
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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

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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

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What is concentration?

• Amount of solute in a certain amount of
  solventthink about kool-aid
• Solvent what does the dissolving (liquid)
• Solute what is dissolved in the solvent
• Which is more concentrated?

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Passive Transport

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

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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!)

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Diffusion
Dynamic Equilibrium
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For lab

• To the tube, add
• Glucose solution
• Starch

• To the beaker, add
• Water
• Iodine

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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?

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Flea Diffusion Analogy
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Flea Diffusion Analogy
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Flea Diffusion Analogy
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Dynamic Equilibrium
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Simple Diffusion in Cells

• Diffusion Animation
• Diffusion Across a Membrane

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PROBLEM BREAK
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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

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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!

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http//www.linkpublishing.com/video-transport.htm
Brownian_Movement
What About Cells?
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Cells in Hypertonic Solution
HYPERTONIC

• Water moves out of the cell
• Cell shrivels

Low
Hi
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Hypotonic Solution

• Water moves into the cell
• Cell swells
• Animal cell can burst
• Plant cell builds up pressure on cell wall, but
  rigid cell wall keeps it from bursting

HYPOTONIC
Hi
Lo
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Isotonic Solution

• Water moves in and out of the cell
• Cell stays the same size
• Dynamic Equilibrium

ISOTONIC
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Osmosis Animations

• http//www.tvdsb.on.ca/westmin/science/sbi3a1/Cell
  s/Osmosis.htm

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

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

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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

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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/biological2
  0anamations.html

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

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The sodium-potassium pump

• Active Transport requires energy!
• Sodium is pumped out
• Potassium is pumped in
• Animation

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Active transport

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

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

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

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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?

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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?

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FRAYER MODEL BREAK!
Draw example
define
Active transport
Explain your example
Does it require energy? Examples
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VENN DIAGRAM TIME MUWAHAHAHAHA
ACTIVE TRANSPORT
FACILITATED DIFFUSION
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Moving the big stuff
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Exocytosis

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

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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
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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.
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Exocytosis
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Ponder for a moment

• How does exocytosis fit into PROTEIN SYNTHESIS????

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Endocytosis

• Large substances enter the cell
• Cell membrane forms a pit and wraps around
  substance
• Cell membrane pinches off forms a vesicle

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Endocytosis
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Cell Signaling

• Signaling activity
• Modeling Nerves

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Go to picture ?

• http//learn.genetics.utah.edu/content/addiction/d
  rugs/mouse.html

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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.