2: In a water solution, phospholipids form a bilayer where the hydrophobic tails point towards each other on the interior and only the hydrophilic heads are exposed to the water. Phospholipid bilayers are critical components of cell membranes.

Phospholipids spontaneously form bilayer when mixed with water because they have an end that is polar and another that is polar. They are generally referred to as amphiphilic molecules with a hydrophobic fatty acid tail and a hydrophilic phosphate head.

Why do Phospholipids form bilayers? -Phospholipids are amphipathic with a hydrophilic phosphate group and one or two hydrophobic hydrocarbon tails. – They form bilayers because the hydrophobic hydrocarbon tails will be shielded from interacting with water and will form noncovalent interactions.

The phospholipid heads are hydrophilic (attracted to water molecules). In contrast, the phospholipid tails are hydrophobic (repelled by water molecules). phospholipids to form a bilayer, where the head regions face the surrounding water molecules and the opposing tails face each other.

The orientation of these two sections of the phospholipid molecule is crucial to the function of the plasma membrane. The phosphate region is hydrophilic (literally, “water-loving”) and attracts water. The fatty acid region is hydrophobic (literally, “water-hating”) and repels water.

The reason for this is, as stated in your question, it is called a phospholipid bilayer. It’s called like that because it is made out of lipids and it also has phosphate groups, while the bilayer part means it just has two layers. Therefore it is commonly also called a lipid membrane.

Being cylindrical, phospholipid molecules spontaneously form bilayers in aqueous environments. In this energetically most-favorable arrangement, the hydrophilic heads face the water at each surface of the bilayer, and the hydrophobic tails are shielded from the water in the interior.

Lecithin and cephalin both are phospholipids. Lecithin is probably the most common phospholipid which contains the amino alcohol, choline. It is found in egg yolks, wheat germ, and soybeans.

Gangliosides

Sphingolipids are a class of lipids containing a backbone of sphingoid bases, a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named after the mythological sphinx because of their enigmatic nature.

Acetone

Sphingolipid, any member of a class of lipids (fat-soluble constituents of living cells) containing the organic aliphatic amino alcohol sphingosine or a substance structurally similar to it.

Sphingolipids are highly bioactive compounds that participate in the regulation of cell growth, differentiation, diverse cell functions, and apoptosis. They are present in both plant and animal foods in appreciable amounts, but little is known about their nutritional significance.

Sphingolipids are a class of lipids with a polar head group and two nonpolar tails. The core of a sphingolipid is an amino alcohol called sphingosine.

Sphingolipids are regulators of mitochondria-mediated cell death in higher eukaryotes. We found in yeast that within the sphingolipid degradation pathway, the production via Dpl1p and degradation via Hfd1p of hexadecenal are critical for mitochondrial function and cell death.

Definition. Sphingolipids contain a sphingoid base within their structure. Gangliosides are sialic-acid-containing glycosphingolipids.

Sphingomyelin

Instead, the backbone in sphingomyelin is sphingosine, an amino alcohol that contains a long, unsaturated hydrocarbon chain (Figure 12.6). In sphingomyelin, the amino group of the sphingosine backbone is linked to a fatty acid by an amide bond.