Q: What are lipid bilayers?
A: Lipid bilayers are a continuous sheet that forms cell membranes and surrounds most cell organelles.
Q: How do lipid bilayers form?
A: Lipid bilayers form automatically from phospholipids by self-assembly.
Q: What are the heads and tails of phospholipids?
A: Phospholipids have heads that mix with water and tails that reject water.
Q: Where are the tails and heads of phospholipids in a lipid bilayer?
A: The tails come together in the centre of the double layer, and the heads on the outside are surrounded by water.
Q: What do lipid bilayers stop from passing through?
A: Lipid bilayers stop most water-soluble (hydrophilic) molecules and ions from passing through.
Q: How are proteins put in the bilayer of a cell membrane?
A: Proteins are put in the bilayer by enzymes in cells.
Q: What do proteins in the bilayer of a cell membrane do?
A: Proteins in the bilayer of a cell membrane decide which molecules come in and which go out of the cell, such as controlling salt concentrations and pH using ion pumps.