The main difference between lipids and cholesterol is that lipids are one of the three main constituents of the living cells together with carbohydrates and proteins whereas cholesterol is a waxy substance, which is an essential component of the cell membrane.
Lipids and cholesterol are two types of organic compounds present in the body, performing vital functions in the body. Furthermore, the three main types of lipids are triglycerides, phospholipids, and steroids while cholesterol is a sterol, a type of lipid.
Key Areas Covered
1. What are Lipids
– Definition, Types, Importance
2. What is Cholesterol
– Definition, Types, Importance
3. What are the Similarities Between Lipids and Cholesterol
– Outline of Common Features
4. What is the Difference Between Lipids and Cholesterol
– Comparison of Key Differences
Key Terms
Cholesterol, (ULDL), HDL, LDL, Lipids, Phospholipids, Steroids, Triglycerides, VLDL
What are Lipids
Lipids are a class of organic molecules that are insoluble in water, but soluble in organic solvents. Moreover, they are one of the three main constituents of a living cell along with proteins and carbohydrates. The three main types of lipids are triglycerides, steroids, and phospholipids.
Figure 1: Common Lipids
Triglycerides
Triglycerides are natural fats, which are the esters containing a single glycerol molecule attached to three fatty acid molecules. Moreover, fats and oils are the two types of triglycerides classified based on the degree of saturation. Here, oils are the unsaturated forms of triglycerides, which occur in the liquid form in nature. On the other hand, fats are the more saturated forms of triglycerides, which occur as solids in nature. However, the main function of triglycerides is to serve as energy molecules.
Steroids
Steroids are organic molecules with four rings arranged in a specific molecular configuration. The two main types of steroids are steroid hormones and cholesterol. Some hormones in the body such as sex hormones, adrenaline, and cortisol are steroids. On the other hand, cholesterol is produced by the body and it serves as precursors to steroid hormones. However, the main function of steroids is to serve as components of cell membranes, altering membrane fluidity and serving as signaling molecules.
Phospholipids
Phospholipids are derivatives of triglycerides, only containing two fatty acid chains attached to the glycerol molecule. The third component to be attached is a phosphate group, which makes the phospholipids amphipathic. In addition, its diglyceride part is hydrophobic while the phosphate group is hydrophilic. Therefore, phospholipids help in the formation of the lipid bilayer structure, which serves as a selectively permeable barrier in cell membranes.
What is Cholesterol
Cholesterol is a sterol that serves as a precursor of steroid hormones. It also serves as a component of the cell membrane, allowing cell signaling. Moreover, cholesterol helps in the production of vitamin D and bile. It forms the myelin sheath of the axon of myelinated nerves, increasing the speed of signal transmission. Significantly, cholesterol can be taken into the body through diet while the liver is also capable of synthesizing it.
Figure 2: HDL and LDL
Furthermore, a lipid-protein complex known as a lipoprotein is responsible for the transport of cholesterol through the blood. The five types of lipoproteins in the blood are chylomicrons (ULDL), very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein, and high-density lipoprotein (HDL).
- Chylomicrons carry triglycerides from the intestines to the liver, to skeletal muscle, and to adipose tissue.
- VLDLs carry newly synthesized triglycerides from the liver to adipose tissue.
- IDLs are intermediates between VLDL and LDL.
- LDLs carry high amounts of fat molecules including phospholipids, cholesterol, triglycerides, etc. throughout the body.
- And, HDLs collect fat molecules (phospholipids, cholesterol, triglycerides, etc.) from the body’s cells and take it back to the liver.
However, due to their function, LDL is considered as bad cholesterol as its oxidation within the arteries can cause atherosclerosis while HDL is a type of good cholesterol as it carries cholesterol from the body to the liver.
Similarities Between Lipids and Cholesterol
- Lipids and cholesterol are two types of organic compounds present in living organisms.
- They are non-polar and do not dissolve in water.
- Moreover, both can be obtained through diet and some of them are produced by the animal body as well.
- Also, both perform vital functions in the body.
Difference Between Lipids and Cholesterol
Definition
Lipids refer to any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents while cholesterol refers to a compound of the sterol type found in most body tissues. Thus, this is the main difference between lipids and cholesterol.
Significance
Moreover, lipids are one of the three main constituents of living cells while cholesterol is a sterol, which is a type of lipid.
Types
The three main types of lipids are triglycerides, steroids, and phospholipids while the two main types of cholesterols in the body are HDL and LDL.
Importance
Lipids serve as molecules of storing energy, signaling, and acting as structural components of cell membranes while cholesterol and its derivatives are important constituents of cell membranes and precursors of other steroid compounds, but a high proportion in the blood of LDL is associated with an increased risk of coronary heart disease. Thus, this is the functional difference between lipids and cholesterol.
Conclusion
Lipids are one of the three main types of macronutrients present in a living organism. Generally, lipids are insoluble in water. The three main types of lipids in the body are triglycerides, steroids, and phospholipids. Also, lipids serve as energy-storing as well as structural molecules and they involve in signaling. On the other hand, cholesterol is a sterol, which is a type of lipid. The liver can produce cholesterol and the two main types of cholesterol in the body are HDL and LDL. Generally, cholesterol serves as structural components of the cell membrane. High levels of cholesterol in the body can increase the risk of heart disease. Therefore, the main difference between lipids and cholesterol is structure and importance.
References:
1. McCarthy, Karen. “The Three Classifications of Lipids Found in Food and in the Human Body.” Healthy Eating | SF Gate, 14 Dec. 2018, Available Here.
2. Roland, James. “Cholesterol: Is It a Lipid?” Healthline, Healthline Media, 30 July 2018. Available Here.
Image Courtesy:
1. “Common lipids lmaps” By Lmaps at the English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
2. “máu nhiễm mỡ – cholesterol” By LÊ VĂN THẢO (CC BY-SA 2.0) via Flickr
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