Scientists Say: Fatty acid | Science News for Students

Scientists Say: Fatty acid

These tiny chains make up cell membranes, and keep you going when sugar runs out
Oct 24, 2016 — 7:00 am EST
fatty acids

These are examples of fatty acids. They all have long chains of carbon (black) with hydrogens on the outside (gray) in common.

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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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Power Words

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atom     The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and neutrally charged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

carbon     The chemical element having the atomic number 6. It is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

cell     The smallest structural and functional unit of an organism. Typically too small to see with the naked eye, it consists of watery fluid surrounded by a membrane or wall. Animals are made of anywhere from thousands to trillions of cells, depending on their size. Some organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create for that organism or process. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature, humidity and placement of components in some electronics system or product.

fat     A natural oily or greasy substance occurring in animal bodies, especially when deposited as a layer under the skin or around certain organs. Fat’s primary role is as an energy reserve. Fat is also a vital nutrient, though it can be harmful to one’s health if consumed in excess amounts.

fatty acid     A large molecule made of up chains of carbon and hydrogen atoms linked together. Fatty acids are chemical building blocks of fats in foods and the body.

glycerol     A colorless, odorless, sticky syrup that can be used as an antifreezing agent.

hydrogen     The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues.

liquid     A material that flows freely but keeps a constant volume, like water or oil.

membrane     A barrier which blocks the passage (or flow through of) some materials depending on their size or other features. Membranes are an integral part of filtration systems. Many serve that same function as the outer covering of cells or organs of a body.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

oxygen     A gas that makes up about 21 percent of the atmosphere. All animals and many microorganisms need oxygen to fuel their metabolism.

phosphate     A chemical containing one atom of phosphorus and four atoms of oxygen. It is a component of bones, hard white tooth enamel, and some minerals such as apatite.

triglyceride     The main ingredient of many animal fats and oils. A high level of triglycerides in the blood puts a person at risk for heart disease or stroke.