What is the Difference Between Fatty Acids and Triglycerides

The main difference between fatty acids and triglycerides is that fatty acids are one of the two types of structural components of triglycerides, whereas triglycerides are the main constituent of fat. Furthermore, fatty acids contain long-chain hydrocarbons terminated with a carboxylic acid functional group while triglycerides contain three fatty acids which are chemically linked to a glycerol molecule.  

Fatty acids and triglycerides are two types of lipids primarily consisting of carbon and hydrogen atoms. They play numerous and diverse purposes in the structure and function of organisms. 

Key Areas Covered 

1. What are Fatty Acids
     – Definition, Structure, Function
2. What are Triglycerides
     – Definition, Structure, Function
3. What are the Similarities Between Fatty Acids and Triglycerides
     – Outline of Common Features
4. What is the Difference Between Fatty Acids and Triglycerides
     – Comparison of Key Differences

Key Terms 

Fatty Acids, Lipids, Saturated Fat, Triglycerides, Unsaturated Fat

What are Fatty Acids 

Fatty acids are long chains of hydrocarbons with a terminal carboxylic acid group. Due to their long hydrocarbon chains, fatty acids are hydrophobic. Generally, there are two types of fatty acids: saturated fatty acids and unsaturated fatty acids. Saturated fatty acids contain single bonds between all carbons of the hydrocarbon chain, while unsaturated fatty acids contain at least one double bond between carbon atoms of the hydrocarbon chain. Therefore, saturated fatty acids have a straight and flexible carbon backbone, while unsaturated fatty acids have ‘kinks’ in their carbon backbone. Thus, saturated fatty acids are solids at room temperature, while unsaturated fatty acids are liquids.

Figure 1: Fatty Acids

Furthermore, all fatty acids can be divided into two according to the ability of the body to synthesize them through biochemical reactions. They are essential fatty acids and non-essential fatty acids. Basically, the human body is unable to synthesize essential fatty acids through biochemical reactions. Therefore, they have to be included in the food. Also, the two essential fatty acids for the human body are linoleic acid and alpha-linoleic acid. In addition to these, the human body can synthesize non-essential fatty acids through regular biochemical reactions. 

What are Triglycerides 

Triglycerides are the main constituent of body fat of vertebrates as well as vegetable fat. Generally, they are the esters derived from glycerol and three fatty acids. The two main types of triglycerides are saturated fat and unsaturated fat. Hydrocarbon chains of fatty acids are saturated in saturated fat, while hydrocarbon chains of fatty acids contain double bonds in unsaturated fat. Also, saturated fat has higher melting points and therefore, they are solid at room temperature. On the other hand, unsaturated fat has comparatively low melting points, and they are liquids at room temperature. Moreover, triglycerides with a single double bond in the hydrocarbon chain of fatty acids are monounsaturated fatty acids while triglycerides with two or more double bonds in the hydrocarbon chain of fatty acids are polyunsaturated fatty acids.

Figure 2: Triglyceride

Moreover, in enterocytes, the re-esterification of monoglycerides forms chylomicrons, which ultimately mix into the blood. After that, tissues of the body capture chylomicrons to use as an energy source. Furthermore, the main sites for the endogenous triglyceride synthesis are the liver and adipose tissue. Triglycerides in the adipose tissue represent one of the energy sources of the body. The enzymatic action of the hormone-sensitive lipase is responsible for the mobilization of fatty acids in the adipose tissue.  

Similarities Between Fatty Acids and Triglycerides 

• Fatty acids and triglycerides are two types of lipids. 
• Moreover, they are primarily made up of carbon and hydrogen atoms. 
• They also play a vital role in constructing biological membranes and as energy and carbon-storing molecules. 
• In addition to the above, they can be a source of nutrients. 

Difference Between Fatty Acids and Triglycerides 

Definition 

Fatty acids refer to a carboxylic acid, consisting of a hydrocarbon chain and a terminal carboxyl group, especially any of those occurring as esters in fats and oils, while triglycerides refer to an ester formed from glycerol and three fatty acid groups, serving as the main constituents of natural fats and oils. 

Significance 

Fatty acids are one of the two types of structural components of triglycerides, while triglycerides are the main constituent of fat.  

Structure 

While fatty acids contain long-chain hydrocarbons terminated with a carboxylic acid functional group, triglycerides contain three fatty acids, which are chemically linked to a glycerol molecule.  

Function  

Furthermore, fatty acids play a key role in biological processes and the construction of biological membranes while triglycerides play an important role in metabolism as an energy source. 

Conclusion 

Fatty acids are one of the two structural components of a triglyceride while the second being glycerol. Moreover, three fatty acids connect to glycerol to form a triglyceride. Besides, fatty acids are important in the formation of biological membranes. On the other hand, triglycerides are the main constituent of fat. Also, they serve as an energy source of the body. Therefore, the main difference between fatty acids and triglycerides is their structure and function. 

References:

1. OpenStax. “Lipids .” Lumen|Microbiology, Available Here.

Image Courtesy:

1. “Rasyslami” By The original uploader was at English Wikipedia. (CC BY-SA 3.0) via Commons Wikimedia   
2. “Fat triglyceride shorthand formula” By Wolfgang Schaefer – author (Public Domain) via Commons Wikimedia