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Plasma Membrane
Notes
CHARACTERISTICS:
• Maintains homeostasis (balance with environment)
• Selective permeability – allows some molecules into the cell while keeping others out.
Example of selective permeability – screen door keeps something out (bugs, pets, small children) and allows something through (small things)
STRUCTURE:
Phospholipids:• Lipids (fatty acid) with a phosphate
group attached.
• Polar head and non-polar tails
• Hydrophilic (likes water) head and hydrophobic (afraid of water) tail
Tail
Hydrophilic and Hydrophobic
Hydrophilic: “likes water”
Hydrophobic: “fears water” - repels water
Carrier Proteins• Found in plasma membrane (also
known as transport proteins)
• Allows larger substances to move through the plasma membrane.
Cholesterol molecule• Helps stabilize the phospholipids
• Prevents the fatty acid chains of the phospholipids from sticking together