THE CELL
STRUCTURE AND FUNCTION OF THE CELL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The phospholipid bilayer can easily move around (is fluid) allowing small molecules to pass through.
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The phospholipid bilayer can not easily move around (is static), therefore is can not allow any molecules to pass through.
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The phospholipid bilayer has the ability to open and close like a draw bridge.
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The phospholipid bilayer will only allow large particles to pass through.
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Detailed explanation-1: -Permeability of phospholipid bilayers. Small uncharged molecules can diffuse freely through a phospholipid bilayer. However, the bilayer is impermeable to larger polar molecules (such as glucose and amino acids) and to ions.
Detailed explanation-2: -The simplest mechanism by which molecules can cross the plasma membrane is passive diffusion. During passive diffusion, a molecule simply dissolves in the phospholipid bilayer, diffuses across it, and then dissolves in the aqueous solution at the other side of the membrane.
Detailed explanation-3: -The phospholipid bilayer consists of two layers of phospholipids, with a hydrophobic, or water-hating, interior and a hydrophilic, or wate r-loving, exterior. The hydrophilic (polar) head group and hydrophobic tails (fatty acid chains) are depicted in the single phospholipid molecule.
Detailed explanation-4: -(c) Describe the characteristics of the phospholipid bilayer that permit small hydrophobic lipid molecules to pass directly across the membrane. The phospholipid bilayer’s phospholipid molecules each have a hydrophilic head and two hydrophobic tails.
Detailed explanation-5: -Only materials that are relatively small and nonpolar can easily diffuse through the lipid bilayer. Large particles cannot fit in between the individual phospholipids that are packed together, and polar molecules are repelled by the hydrophobic/nonpolar lipids that line the inside of the bilayer.