Unit 2 · 2.4 — Membrane Permeability [cite: 9, 28]

Everything to learn here

• Concept: Small, uncharged, nonpolar molecules (e.g., $N_2$, $O_2$, $CO_2$) pass freely across the membrane, whereas large molecules, polar molecules, and ions require transport proteins [cite: 13].
• Vocabulary: Selective Permeability — the inherent property of biological membranes that allows some substances to cross more easily than others [cite: 13, 32].
• Vocabulary: Cell Wall — a rigid outer boundary found in plants, fungi, and prokaryotes providing structural integrity and acting as an initial permeability barrier [cite: 13, 33].
• Skill: FRQ Task Verb "Determine" — Determine the specific mechanism of permeability for a given molecule based on its chemical polarity, size, and charge [cite: 17, 22].
• Concept: Explain how the hydrophobic interior of the phospholipid bilayer creates selective permeability for different molecules.
• Concept: Describe how cell walls provide structural support and act as a permeability barrier in various organisms.
• Concept: Describe how cell walls in plants and microbes provide protection against osmotic lysis and structural integrity.

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