Name a Structural Difference Between Triglycerides and Phospholipids

are a family of organic compounds that are more often than not insoluble in water, significant they do not mix well with water.
At that place are three main types of lipids: triglycerides, phospholipids, and sterols.
On this page, nosotros’ll acquire about the structures of these three types of lipids, as well as their functions in the body and where you can notice them in foods.

Triglycerides

are the main grade of lipids in the torso and in foods. More than 95 percentage of lipids in the diet are in the class of triglycerides, some having a visible presence and some hidden in foods. Concentrated fats (butter and vegetable oil, for instance) and marbling of fatty in meat are plain visible. But fatty can also be hidden in foods, as in baked appurtenances, dairy products like milk and cheese, and fried foods. Naturally occurring triglycerides are establish in many foods, including avocados, olives, corn, and basics. We usually telephone call the triglycerides in our nutrient “fats” and “oils.” Fats are lipids that are solid at room temperature, whereas oils are liquid. The terms fats, oils, and triglycerides are frequently used interchangeably. In this unit, when nosotros use the discussion fat, we are referring to triglycerides.

Figure 5.5.
95% of fats in the nutrition are in the form of triglycerides. Sterols (like cholesterol) make upward nearly 3% of dietary fatty intake and phospholipids brand up roughly two% of dietary fat intake.

The structure of a triglyceride is made upward of glycerol and three fatty acids.



is the three-carbon backbone of triglycerides, while


are longer chains of carbon molecules attached to the glycerol backbone. The “glyceride” in the discussion “triglyceride” refers to this glycerol backbone, while the “tri” refers to the fact that at that place are iii fatty acids fastened. Fatty acids are called acids because they take an acrid group (−COOH) on one terminate of a carbon concatenation. A monoglyceride contains glycerol with i fat acid attached, and a diglyceride contains glycerol with 2 fatty acids attached.

Figure five.6.

The chemic structure of a triglyceride, showing the glycerol backbone and 3 attached fatty acids.

Figure 5.7.

The structure of a

triglyceride

is often depicted equally a simplified drawing of the glycerol courage and three fatty acids.

There are unlike types of fatty acids, and triglycerides can contain a mixture of them. Fatty acids are classified past their carbon chain length and caste of saturation. Foods incorporate different proportions of fatty acid types, and this influences affliction risks associated with dietary patterns. We will take a closer expect at these differences, forth with food sources, in the adjacent section.

Phospholipids

are found in both plants and animals simply make upward only about 2 per centum of dietary lipids. Still, they play many of import roles in the body and in foods. Phospholipids tin can also be synthesized by the body, so they don’t accept to be consumed in the diet.

Phospholipids are similar in structure to triglycerides (Figure v.8). Similar triglycerides, phospholipids take a glycerol backbone. Simply unlike triglycerides, phospholipids only have two fatty acid molecules attached to the glycerol backbone, while the third carbon of the glycerol courage is bonded to a phosphate group—a chemical group that contains the mineral phosphorus.

Figure. five.viii.

The structural deviation between a triglyceride (on the left) and a phospholipid (on the right) is in the third carbon position, where the phospholipid contains a phosphate group instead of a fatty acid.

The unique structure of phospholipids makes them both fat- and h2o-soluble, or


. The fatty-acids are hydrophobic (dislike water), and the phosphate group and glycerol are hydrophilic (attracted to water).

Figure v.9.
A phospholipid molecule consists of a polar phosphate “head,” which is hydrophilic, and a non-polar lipid “tail,” which is hydrophobic.

The amphiphilic nature of phospholipids makes them very useful for several functions in the body. Every cell in the body is encased in a membrane equanimous primarily of a double layer of phospholipids (also known as the phospholipid bilayer), which protects the inside of the cell from the outside environs while at the same time assuasive for transport of fatty and water through the membrane. Phospholipids also play a function in transporting fats in the blood, as we’ll learn later in this unit.

Figure 5.10.
The phospholipid bilayer consists of 2 adjacent sheets of phospholipids, arranged tail to tail. The hydrophobic tails associate with one another, forming the interior of the membrane. The polar heads contact the fluid inside and outside of the jail cell.

Some other of import role of phospholipids is to act as


. Emulsions are mixtures of two liquids that do not commonly mix (oil and water, for example). Without an emulsifier, the oil and water separate out into two layers. Because of their ability to mix with both water and fat, phospholipids are ideal emulsifiers that can proceed oil and h2o mixed, dispersing tiny oil aerosol throughout the water. Lecithin—a phospholipid establish in egg yolk, soybean, and wheat germ—is oft used as a food emulsifier. Emulsifiers also play an important role in making food appetizing; their inclusion in foods like sauces and creams makes for a smoother texture and prevents the oil and water ingredients from separating out. They also tin extend shelf life.

Sterols

take a very different structure from triglycerides and phospholipids. Most sterols exercise non contain any fatty acids merely rather are multi-band structures, similar to chicken wire. They are circuitous molecules that contain interlinking rings of carbon atoms, with side chains of carbon, hydrogen, and oxygen attached.

is the best-known sterol considering of its role in heart illness. It forms a large role of the fatty plaques that narrow arteries and obstruct blood flow in


. However, cholesterol also has many essential functions in the torso. Similar phospholipids, cholesterol is present in all trunk cells equally it is an of import substance in cell membrane structure. Cholesterol is besides used in the body as a precursor in the synthesis of a number of important substances, including vitamin D, bile, and sexual activity hormones such as progesterone, testosterone, and estrogens.

Figure five.11.

Cholesterol is made up of multiple carbon rings bonded together.

Cholesterol is non an essential food; it does non need to be consumed in the diet, considering it is manufactured in the liver.
Only foods that come from beast sources contain cholesterol.
Cholesterol is plant in foods like meat, poultry, fish, egg yolks, butter, and dairy products made from whole milk.

Plant foods practice not comprise cholesterol, but sterols institute in plants resemble cholesterol in construction. Constitute sterols inhibit cholesterol absorption in the human body, which tin contribute to lower cholesterol levels, specially lower LDL (“bad”) cholesterol levels. Found sterols occur naturally in vegetable oils, basics, seeds, and whole grains. In addition, some foods like margarines and dressings are fortified with plant sterols.

Attributions:

• Lindshield, B. L. Kansas Country University Human Nutrition (FNDH 400) Flexbook. goo.gl/vOAnR, CC BY-NC-SA four.0
• University of Hawai‘i at Mānoa Food Science and Human Nutrition Programme, “Digestion and Absorption of Lipids,” CC BY-NC iv.0

Image Credits:

• Figure 5.5. “Types of Fat” past Allison Calabrese is licensed nether CC Past 4.0
• Figure five.6. “The Structure of a Triglyceride” by Allison Calabrese is licensed under CC By 4.0
• Effigy 5.7. “Uncomplicated Triglyceride Diagram” by Alice Calahan is licensed under CC By-SA 4.0
• Figure v.8. “The Difference Betwixt Triglycerides and Phospholipids” by Allison Calabrese is licensed nether CC Past iv.0
• Effigy five.nine. “Phospholipid Structure” by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix is licensed under CC BY 4.0
• Figure 5.x. “Phospolipid Bilayer” past J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix is licensed under CC BY 4.0
• Figure 5.11. “Cholesterol Chemical Structure” past Wesalius is in the Public Domain