Choline is often found in their hydrophilic "heads," contrasted with their hydrophobic "tails.
The breakdown of one of these compounds, PIP2, is the initial step in the IP3/DAG signaling pathway. A type of these compounds forms amide, rather than ester linkages because its backbone is made of sphingosine, and is called sphingomyelin. The movement of these compounds from one leaflet to the other is catalyzed by flippases. In the cell, liposomes are composed of these molecules, which have a three-carbon triol backbone from glycerol. Choline is often found in their hydrophilic "heads," contrasted with their hydrophobic "tails." These molecules allow only small nonpolar molecules to enter the cell. For 10 points, name these molecules that make up the plasma membrane.
The breakdown of one of these compounds, PIP2, is the initial step in the IP3/DAG signaling pathway.
phospholipids [accept sphingolipids or sphingomyelin before mention; prompt on "lipids"; do not accept or prompt on "fatty acids" or "cell membranes" or "lipid bilayers"]