Phospholipid Bilayer Structure — NEET Biology
✅ Asked in NEET 2022These studies showed that the cell membrane is mainly composed of lipids and proteins. The major lipids are phospholipids that are arranged in a bilayer. Also, the lipids are arranged within the membrane with the polar head towards the outer sides and the hydrophobic tails towards the inner part. This ensures that the nonpolar tail of saturated hydrocarbons is protected from the aqueous environment. In addition to phospholipids, membrane also contains cholesterol.
NTA tests whether students understand how lipids arrange in the cell membrane to create a selective barrier. The phospholipid bilayer has polar heads facing outward (toward water) and hydrophobic tails facing inward (away from water). Students commonly mistake the orientation, thinking tails face outward, which leads to wrong answers about membrane permeability and transport. Remember: Polar heads = water-loving (outside), Hydrophobic tails = water-fearing (inside). This hydrophobic core blocks water-soluble molecules from crossing, making the membrane selectively permeable. This arrangement is fundamental for understanding passive transport, active transport, and cholesterol's role in membrane fluidity—all frequent NEET topics.
Which type of substance would face difficulty to pass through the cell membrane? NEET 2022 Phase 2
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