Download - Ch 7.2 Plasma Membrane
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Ch 7.2 Plasma Membrane
• Yesterday we talked about things all cells have. One of those things was the plasma membrane.
• Can you remember the other two?
• Lets review from yesterday
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Prokaryote Eukaryote
• contains nucleus• contains organelles (membrane-bound structures within cell)• mostly multicellular
Two Basic Cell Types
• no nucleus• no organelles• mostly unicellular• very small in size• ex. bacteria, archaebacteria
• ex. plants, animals, yeast
ALL cells have 1. plasma membrane 2. Ability to break down molcules
3. genetic material
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• Plasma Membrane- a boundary that controls what leaves and enters the cell.
Why is it important to control what leaves and enters the cell???
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• All prokaryotes and eukaryotes have a plasma membrane
• Surrounds the cell, providing protection and support
• Helps a cell maintain homeostasis, by regulating what enters and leaves the cell
• Selectively Permeable: Only allows certain materials through
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The plasma membrane has 4 main components.
1.Phospholipid Bilayer2.Transport proteins
3. Cholesterols 4.Carbohydrates
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Structure of the Plasma Membrane
• The plasma membrane is composed of a phospholipid bilayer – two layers of phospholipids are arranged tail to tail.
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Lipids – make up the lipid bilayera. Hydrophobic region (between layers)b. Hydrophilic region
(inside and outside the cell)
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Hydrophilic = Water Loving
Hydrophobic= Water Fearing
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Other Components of the Plasma Membrane
Within the Phospholipids there are 3 other things.
Do you remember????
•Transport proteins • Cholesterols •Carbohydrates
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Other Components of the Plasma Membrane
2. Transport proteins - create tunnels through which certain substances enter and leave the cell.
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Other Components of the Plasma Membrane
3. Cholesterols contribute to the fluidity of the plasma membrane in that they prevent the fatty-acid tails from sticking together.
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Other Components of the Plasma Membrane
4. Carbohydrates attached to proteins stick out from the plasma membrane and help identify the cell
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It looks like this
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Fluid Mosaic Model• http://www.susanahalpine.com/anim/Life/me
mb.htm
• The components of the plasma membrane are in constant motion sliding past each other.
• The phospholipids in the bilayer create a “sea” in which other molecules can float, hence “fluid” and “mosaic” because there are many components which appear as a pattern or a mosaic.
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Ok what???
• Fluid mosaic model- All the parts of the plasma membrane are moving all the time
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Review/Study Questions
• How does the plasma membrane help maintain homeostasis?
• What does it mean if something is selectively permeable?
• What makes up the plasma membrane?• Why are the phospholipids arranged like they
are?
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Plasma Membrane Poster
On your BLANK PAPER complete the following: 1. Title: Plasma Membrane 2. Draw a plasma membrane in color (page 188!)) 3. Label the:
* Phospholipids * Proteins * Carbohydrates * Cholestrols * Inside the cell * Hydrophobic areas in BLUE (water fearing!) * Hydrophilic areas in RED (water loving)
4. In the lower RIGHT corner, write your name
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Questions on Back–Define plasma membrane–What is the plasma membranes function?–Tell me what the cholesterol does–Tell me what the transport protein does–Tell me what the carbohydrate does