Membrane Permeability
Elijah Ramirez
6 min read
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Study Guide Overview
This study guide covers cell membranes and cell walls. For membranes, it reviews membrane structure and permeability, focusing on the phospholipid bilayer, selective permeability, and transport of molecules. It also discusses diffusion. For cell walls, the guide examines their function, structural support, and composition in different organisms (plants, fungi, bacteria).
#🧬 Cell Membrane & Walls: Your Night-Before Review
Hey! Let's get you feeling super confident about cell membranes and walls. We'll make sure everything's crystal clear for tomorrow.
#🧱 Membrane Structure & Permeability
#Selective Permeability: The Gatekeeper 🚪
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The cell membrane is selectively permeable, meaning it controls what goes in and out. Think of it like a bouncer at a club, not everyone gets in!
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This is all thanks to the phospholipid bilayer: hydrophilic (water-loving) heads face outwards, and hydrophobic (water-fearing) tails face inwards.
Image: The phospholipid bilayer with hydrophilic heads and hydrophobic tails.
- Key Point: The hydrophobic tails are the barrier. They repel polar and charged molecules, making it tough for them to cross without help.
#What Can Pass Through? 🤔
- Freely Cross (No Help Needed): Small, nonpolar molecules like O2, CO2, and N2. They slip right through the hydrophobic region.
- Need Help (Transport Proteins):
- Large molecules
- Polar (hydrophilic) molecules
- Ions (charged particles)
- Even small, polar, uncharged molecules like water need help (aquaporins) to cross in large quantities.
**A...
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