Fatty acid (noun, “FAT-ee acid”)
A fatty acid is a common kind of molecule in living things. All fatty acids have share a similar structure: At the core is a long chain of carbon atoms linked together. The carbons have hydrogens bonded on their outsides. At one end, the chain is linked to a carboxylic acid. That’s a quartet of one carbon, two oxygens and a hydrogen, grouped together.
When two fatty acid chains pair together with a phosphate group (a phosphorous atom surrounded by oxygen atoms) at their head, they form a phospholipid. The phosphate end loves water. The fatty acid end does not. To protect themselves in a liquid environment, groups of phospholipids will self-organize. The water-loving ends point out toward water, while the water-hating ends pair with each other. A double layer of phospholipids forms something important — a membrane. Every single cell in your body is surrounded by one.
If three fatty acid chains get together, another structure can link them. It is a glycerol (a very short three-carbon chain). And this forms a triglyceride. These molecules are the building blocks of body fat. The body can quickly break down this body fat for energy when no food is available, protecting us from starvation.
In a sentence
Bacteria in the gut release fatty acids, and one of them — called priopionate — may help people eat less.
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