Discuss the permeability of the cell membrane to different sizes and classes of molecules.

Question

﻿Discuss the permeability of the cell membrane to different sizes and classes of molecules.

Accepted Answer

∻Answer∻ ⚹ The cell membrane is selectively permeable, allowing certain molecules to pass through while restricting others based on size, polarity, and the presence of specific transport mechanisms. ⚹ ∻Solution∻ ‖ a ⋮ Small nonpolar molecules: These can diffuse directly through the lipid bilayer without the need for transport proteins. Examples include O₂ and CO₂. ‖ ‖ b ⋮ Small uncharged polar molecules: These molecules, such as water and urea, can pass through the membrane, but their permeability is lower than that of nonpolar molecules. Water can also move through aquaporins, specialized channels that increase its permeability. ‖ ‖ c ⋮ Large polar molecules and ions: These substances cannot easily cross the lipid bilayer due to their size and charge. They require specific transport proteins, such as channels and carriers, to facilitate their movement across the membrane. ‖ ‖ d ⋮ Macromolecules: Large molecules like proteins and polysaccharides typically require vesicular transport mechanisms such as endocytosis or exocytosis to enter or exit the cell. ‖ ∻Key Concept∻ ⚹ Selective permeability of the cell membrane ⚹ ∻Explanation∻ ⚹ The cell membrane's selective permeability is due to its structure, which allows it to discriminate between different types of molecules, permitting some to pass while restricting others. ⚹◊How does the size of a molecule affect its ability to pass through the cell membrane?⍭ Generate me a similar question◊

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