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Membrane Permeability Explorer

Discover how cell membranes selectively control what enters and exits the cell! The phospholipid bilayer acts as a barrier, but different molecules have different abilities to cross it. Small, nonpolar molecules pass easily, while large or charged molecules need special help.

Explore how molecule size, polarity, and membrane proteins affect permeability!

PEEBEDU

Membrane Permeability Explorer

Molecules

Transport Channels

Variables

(Higher temp = faster movement & more permeability)

Key:
O₂ (Sm, NP)
N₂ (Sm, NP)
CO₂ (Sm, NP)
Steroid (Sm, NP)
Water (Sm, P)
Glucose (Lg, P)
Na⁺ (Ion)
K⁺ (Ion)
Protein (VLg, P)
Concentrations (Extracellular | Cytosol):
O₂: 0 | 0   N₂: 0 | 0   CO₂: 0 | 0   Steroid: 0 | 0
Water: 0 | 0   Glucose: 0 | 0
Na⁺: 0 | 0   K⁺: 0 | 0   Protein: 0 | 0
Channels: None active.

Test Your Understanding

1. Which type of molecule can pass through the phospholipid bilayer most easily?
2. Which property of the phospholipid bilayer makes it selectively permeable?
3. Why do ions like Na⁺ and K⁺ require channel proteins to cross the membrane?
4. How do large polar molecules like glucose typically cross the cell membrane?