cellular transport. about cell membranes 1.all cells have a cell membrane 2.functions: a.controls...
TRANSCRIPT
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Cellular Transport
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About Cell Membranes
1.All cells have a cell membrane
2.Functions: a.Controls what enters
and exits the cell to maintain an internal balance called homeostasis
b.Provides protection and support for the cell
TEM picture of a real cell membrane.
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3.Structure of cell membrane
Lipid Bilayer -2 layers of phospholipidsa.Phosphate head is polar
(water loving)
b.Fatty acid tails non-polar (water fearing)
c.Proteins embedded in membrane
About Cell Membranes (continued)
Phospholipid
Lipid Bilayer
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Proteins
Membrane movement animation
Polar heads love water & dissolve.
Non-polar tails hide from water.
Carbohydrate cell markers
Fluid Mosaic Model of the
cell membrane
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• 4. Cell membranes have pores (holes) in it
a.Selectively permeable: Allows some molecules in and keeps other molecules out
b.The structure helps it be selective!
About Cell Membranes (continued)
Pores
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Outside of cell
Inside of cell (cytoplasm)
Lipid Bilayer
Proteins
Transport Protein Phospholipids
Carbohydratechains
Structure of the Cell Membrane
Go to Section:
Animations of membrane
structure
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Types of Cellular Transport
• Passive Transport
cell doesn’t use energy1. Diffusion
2. Facilitated Diffusion
3. Osmosis
• Active Transport
cell does use energy1. Protein Pumps
2. Endocytosis
3. Exocytosis
This is gonna
be hard work!!
high
low
Weeee!!!
•Animations of Active Transport & Passive
Transport
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Passive Transport• cell uses no energy
• molecules move randomly
• Molecules spread out from an area of high concentration to an area of low concentration.
• (HighLow)• Three types:
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3 Types of Passive Transport
1. Diffusion
2. Facilitative Diffusion – diffusion with the help of transport proteins
3. Osmosis – diffusion of water
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Passive Transport: 1. Diffusion
1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration.
(High to Low)
• Diffusion continues until all molecules are evenly spaced (equilibrium is reached.
http://bio.winona.edu/berg/Free.htm
Simple Diffusion Animation
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2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane a.Transport Proteins are
specific – they “select” only certain molecules to cross the membrane
b.Transports larger or charged molecules
Facilitated diffusion (Channel Protein)
Diffusion (Lipid
Bilayer)
Passive Transport: 2. Facilitated Diffusion
Carrier Protein
A B
• http://bio.winona.edu/berg/Free.htm
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High Concentration
Low Concentration
Cell Membrane
Glucosemolecules
Proteinchannel
Passive Transport: 2. Facilitated Diffusion
Go to Section:
Transport Protein
Through a
Cellular Transport From a-High
Low
• Channel Proteins animations
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• 3.Osmosis: diffusion of water through a selectively permeable membrane
• Water moves from high to low concentrations
•Water moves freely through pores.
•Solute (green) to large to move across.
Osmosis animation
Passive Transport: 3. Osmosis
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Hypotonic Solution
Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!
• Osmosis Animations for
isotonic, hypertonic, and hypotonic
solutions
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Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)
Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!
• Osmosis Animations for
isotonic, hypertonic, and hypotonic
solutions
shrinks
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Isotonic SolutionIsotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)
• Osmosis Animations for
isotonic, hypertonic, and hypotonic
solutions
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What type of solution are these cells in?
A CB
Hypertonic Isotonic Hypotonic
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Active Transport
•cell uses energy
•actively moves molecules to where they are needed
•Three Types:
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Types of Active Transport
1. Protein Pumps -transport proteins that require energy to do work
•Example: Sodium / Potassium Pumps are important in nerve responses.
Sodium Potassium Pumps (Active Transport using proteins)
Protein changes shape to move molecules: this requires energy!
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Types of Active Transport
• 2. Endocytosis: taking bulky material into a cell • Uses energy• Cell membrane in-folds
around food particle• “cell eating”• forms food vacuole &
digests food• This is how white blood
cells eat bacteria!
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Types of Active Transport
3. Exocytosis: Forces material out of cell in bulk• membrane surrounding the
material fuses with cell membrane
• Cell changes shape – requires energy
• EX: Hormones or wastes released from cell
Endocytosis & Exocytosis animations
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Practical experiments1- diffusion
two groups • Group (1)• steps:
1- put mix. Of glucose and starch in a cellophane membrane ( as a dialysis bag).
2- let the cellophane bag in a beaker contains 50 ml water and let them for 30 min.
3- let after the time finish we do two tests:
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Benedict test:5 drops of solution in the beaker + 5 drops of Benedict reagent the heating on direct flame
Observation : orange color
Conclusion:The small molecules of glucose transported through the cellophane membrane
Diffusion happened
Iodine test:5 drops of the solution + 5 drops of iodine
Color doesn’t change
The molecules of starch didn’t pass though the membrane
No diffusion
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Group (2)
• steps:• 1- put 20 ml of iodine in a cellophane
membrane ( as a dialysis bag).• 2- let the cellophane bag in a beaker
contains 50 ml starch and let them for 30 min.
• The observation:• The white Color of starch in the beaker turns
to blue
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• Conclusion:
The small particles of iodine transported through the cellophane membrane to starch in the beaker
Diffusion happened
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2- osmosis
• Group (1):
• Hypertonic solution
Group (2):Hypotonic solution
Hyper tonic solution
A piece of potato
Hypotonic solution
A piece of potato
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The steps
• 1- put 50 ml of the solution ( hyper or hypo tonic )in a clean beaker.
• 2- weight a piece of potato (weight before).
• 3- put the potato in the beaker an let them for 30 min.
• 4- weight the potato again (weight after).
• See the different in the weight before and after putting it in the solusion.
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observation
• In case of hypertonic solution
• The weight after is less than the weight before
In case of hypotonic solution
The weight after is greeter than the weight before
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conclusion• In case of
hypertonic solution
• Water moves out of the cell into the solution
• Cell shrinks then happened plasomlysis
In case of hypotonic solution
Water moves from the solution to the cell
Cell swells the happens cell lyses
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Quiz
• Answer the following questions:
• 1- if you are standing in the ocean should you drink sea water to stay alive? And why?
• 2- why do we wrinkle when we are in the tube too long?
• 3- what happen to snail when you put salt water on it?
• 4- show by drawing the RBCS in hyper, hypo and isotonic solutions.