Role of Fats

Fats are classified as those organic compounds which do not interact with water. Put in simple terms, most substances made of fats will not be miscible with water. The study of the function and structure of fats makes up a sizable part of the study of organic compounds. This is because they make up such substances as oils, fats, wax, membranes and energy-storing molecules in plants and animals.

Structure of Fats

Fats, though not as large as macromolecules (polysaccharides, proteins etc.), are made up of smaller molecules that are arranged in particular combinations. They are classified on the basis of these building block molecules. These classifications also differentiate between the functions and structure of fats:

• Fatty Acids: A part of carboxylic acids made up of a hydrocarbon chain have the terminal group COOH. If the hydroxyl ion (OH) is removed from the carboxylic acid, the remaining fragment is called an acyl group. 

In water, this acid is usually without a hydrogen ion, forming a negatively charged COO or carboxylate group. For this reason, fatty acids are amphipathic i.e. their hydrocarbon chain is hydrophobic and their negatively charged COO end is hydrophilic. 

• Saturated Fatty Acids: These contain single bonded carbon atoms that have formed bonds with as many hydrogen atoms as they can.

• Unsaturated Fatty Acids: These contain double-bonded carbon atoms. The number of such double-bonded pairs of carbon atoms determines whether they are monounsaturated or polyunsaturated.

A kind of special polyunsaturated fatty acid is commonly called trans fat. This kind of fat is synthesised in the stomach of cud-chewing animals and can be created by the hydrogenation of some oils and/or fats. These kinds of fats have been found to be detrimental to metabolic health.

Role of Fats in the Body

There are many important functions of fats in the body. They are as follows:

1. Forming membranes: The vast variety of higher-order organisms (most plants and animals) we see around us are eukaryotic. This means that their cells and their cell organelles are separated from their surrounding environments by membranes. These are called biological membranes and consist of the plasma membrane and other intracellular membranes. The main building blocks of these membranes are glycerophosphates. These are:

• Amphipathic molecules
• Have a head group joined to the core by a phosphate ester link
• Have fatty acid-derived tails that link to the core with ester links
• The core is glycerol

1. Storage of energy: Another important part of the roles of fats in the body is the storage of energy. Energy is stored mostly in the form of triglycerides because they are the most efficient for this function in animals as well as in plants. There are a specialised group of cells called adipocytes that break down triglycerides. This releases energy. This constant process is controlled by the enzyme lipase.

Triglycerides release energy at the rate of about 38kJ/g (9kcal/g). When compared to the 17kJ/g (4kcal/g) of carbohydrates, this is quite a bit higher. That is why triglycerides are preferable for storing energy. The adipose tissue of animals is where the triglycerides are stored. In some animals, they even act as insulation against the cold.

1. Signalling: Cell signalling is the communication that happens among cells and between cells and their environment. Fats are a part of this process. Several fats have been discovered to be cellular messengers and have roles in regulating cellular activity, cellular growth etc. 
2. Emulsification of fats: The process of breaking down the fat into smaller blood cells and makes it easy for enzymes to digest food. Emulsification of fats helps digest fats into fatty acids and glycerol that are easily absorbed by the small intestine.

• Other functions: Fat soluble vitamins such as A, D, E and K are fats and are also essential nutrients needed by organisms. They are stored in the liver and fatty tissue. These are used in several functions in the body. Acyl-carnitine transports fatty acids to the mitochondria. Polyprenols and some of their derivatives transport oligosaccharides into and out of the membrane.

Metabolism

Triglycerides, sterols and biological membrane fats (mostly phosphofats) are the main fats in the diets of most animals, including humans. These are metabolised in the following ways:

1. Biosynthesis:

• Surplus carbohydrates in animals are converted into triglycerides. This is done by synthesising fatty acids with the help of acetyl-CoA which is followed by the esterification of the fatty acids. This process is called lipogenesis. The acids can then be converted into triglycerides.
• Unsaturated fatty acids are synthesised by introducing the double bond by a chemical reaction called a desaturation reaction.
• Triglycerides are synthesised in the endoplasmic reticulum.

1. Degradation:

• Fatty acids are broken down in the cell by a process called beta-oxidation. Most fatty acids are oxidised by a process that is almost identical to the reversal of the synthesis of fatty acids.
• Unsaturated fatty acids require additional steps which involve enzymes for degradation.

Role of Fats

Fats play a wide range of roles in the functioning of organisms. Some of which are as follows:

• The fat in the body is stored in the form of fats. These include triglycerides, cholesterol and phospho fats.
• Fats need to be included in the dirt to facilitate the absorption of fat-soluble vitamins like A, D, E and K.
• Linoleic acid is a major component of most plant-based oils and fats. These are mostly omega-6 and omega-3 fatty acids. Studies have shown them to be beneficial for the development of infants, alleviating cancer related problems, treating cardiovascular and psychological ailments.
• Biological membranes are thought to be essential to the development of life itself. They separate the cells from their environments, cell organelles that perform specialised tasks and make metabolism and other functions possible. Consequently, the biological importance of fats is also very high since they make up these biological membranes.

Conclusion

Since fats play such an essential role in the body it is very important to understand the structure and function of fats. This understanding helps in solving several metabolism-related problems. Moreover, fats form the building blocks of the three large food groups, namely carbohydrates, proteins and fats. Since the biological importance of fats is so high, studying them is a useful pursuit.