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Cholesterol is an organic compound and a type of sterol present in the blood plasma and animal tissues. The word cholesterol is derived from Greek word chole meaning bile, stereos means solid and -ol meaning alcohol. It is also known as cholesterin and cholesterol alcohol. To produce hormones and the substance required to digest food is obtained from cholesterol. Human body will produce the required cholesterol according to its needs.
| Table of Contents |
Key Terms: Cholesterol, harmons, animal tissue, cell membrane, organic compound, Precursor molecule
Introduction to Cholesterol Formula
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Cholesterol is the waxy substance present in all animal tissues and blood plasma. It plays an important role in structural components of animal cell membranes. Cholesterol and it’s various derivatives are the crucial constituents of cell membranes, the formation of other steroid compounds are also derived from cholesterol. Cholesterol is the waxy, fat-like substance. Human body needs some amount of cholesterol to form hormones and to create substances that help in digestion.
Liver is the main producer of cholesterol, it naturally produces around 80% of the cholesterol required for the body. We also consume cholesterol from various foods we eat like poultry, eggs, dairy products, fish and meat. Regulation of cholesterol is done in the liver. When we consume food, cholesterol from our diet is absorbed in the small intestine, it is then metabolised and stored in the liver, and then secreted by the liver.
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Structure of Cholesterol
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Cholesterol consists of cholestane of the 5,6-position at having double bond as well as 4beta-hydroxy group. Cholesterol is a waxy substance present in animal tissues and blood plasma. Chemically, cholesterol is a compound, and this compound belongs to the steroid family. It is a white or yellowish crystalline substance. It plays a key role in human metabolism.
Structure of Cholesterol
Properties of Cholesterol
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| IUPAC Name | (3β)-cholest-5-en-3-ol |
| Molecular Formula | C27H46O |
| Molecular Mass | 386.664 g/mol |
| Melting Point | 148ºC to 150ºC |
| Boiling Point | 360ºC |
| Density | 1.052 g/cm2 |
| Hydrogen Bond Donor Count | 1 |
| Hydrogen Bond Acceptor Count | 1 |
| Rotatable Bond Count | 5 |
| Solubility | Soluble in acetone, benzene, ether, hexane |
| Solubility in Water | 0.095 mg/L at 30ºC |
| Physical description | Solid |
| Colour/ Form | White or faintly yellow pearly granules or crystals |
| Odour | Almost Odourless |
Function of Cholesterol
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Within the cell membrane, cholesterol plays an important role in intracellular transport, nerve conduction and cell signalling. Cholesterol is required for structural and functional invaginated caveolae and clathrin-coated pits. Cholesterol is also required in caveolae-dependent and clathrin-dependent endocytosis. The biological process of substrate presentation as well as different enzymes used for substrate presentation in self activation is controlled by cholesterol.
Animal cell membranes are roughly accountable for 30% of cholesterol. Maintenance and construction of membranes also to manage fluid in membranes at a wide range of temperatures. Animal cells don’t need to erect cell walls because cholesterol improves membrane packing. By altering membrane fluidity, interacting with phospholipid fatty-acid chains and maintaining membrane integrity the animal cells can change shape and can move. Resulting stable and strong membrane without being rigid.
Cholesterol is converted into biliary fluids by the liver. Then the biliary fluid is processed in gallbladder, which then passes them into the digestive tract in non esterified form. This is recycling of cholesterol. Approximately half of cholesterol is reabsorbed into the bloodstream through the small intestine.
By developing lipid rafts in plasma membranes, cholesterol plays a vital role in cell signalling. Cholesterol with the help of phospholipids can help to speed up propagation of electrical impulses with nerve tissue in multiple layers. Myelin sheath, which is derived from compact layers of Schwann cell membrane, is rich in cholesterol. This provides protection to many nuran fibres, which improves impulse condition.
To carry out many biochemical processes within the cells, cholesterol acts as a precursor molecule. Cholesterol is a precursor molecule for synthesis of Vitamin D and all steroid hormones. Steroid harmones like sex hormones progesterone, estrogens and testosterone as well asadrenal gland harmones cortisol and aldosterone, and their equivalents in calcium metabolism.
Things to Remember
- Cholesterol is a waxy, fat like substance present in animal tissues and blood plasma.
- The molecular formula for Cholesterol is C27H46O
- Cholesterol is white or faintly yellow perly granules or crystals. They are odourless and tasteless organic compounds.
- 80% Cholesterol is produced in the liver. We also consume Cholesterol from our regular diet.
- Cholesterol plays an important role in forming the structure of cell walls
- Cholesterol is used in production of bile acids in the small intestine, which is used in digestion of food.
- Cholesterol is a precursor molecule for synthesis of Vitamin D.
- Cholesterol also acts as a precursor molecule in production of few hormones.
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| Chapter Related Concepts | ||
|---|---|---|
| Carbohydrate Metabolism | RNA and DNA | |
| Cellulose | Fats and Oils | Sucrose |
Sample Questions
Ques. What is cholesterol? And states its molecular formula? (2 Marks)
Ans. Cholesterol is the waxy, fatty substance present in blood plasma and animal tissue. Chemically it is an organic compound and a member of the steroid family. It is produced in the liver and also consumed by everyday diet.
Molecular formula: C27H46O
Ques. What is cholesterol recycling? (2 Marks)
Ans. Cholesterol is produced in the liver. Liver synthesises cholesterol and produces biliary fluids. The biliary fluid is then passed through the gallbladder and processed. After processing in gallbladder the biliary fluid passes through the digestive tract in non esterified form. The whole process is recycling of cholesterol. Almost 50% of cholesterol is reabsorbed by the small intestine and passed into the bloodstream.
Ques. What is the effect of cholesterol on lipid bilayer? (2 Marks)
Ans. Cholesterol is a type of lipid which is a water insoluble substance, but soluble in alcohol and ether. When there is a large amount of cholesterol produced, it works as a permeability barrier for the membrane by adding conformational ordering of the lipid chains. It also maintains and improves mechanical stiffness by maintaining membrane fluid. When cholesterol level is low, the mobility of the first carbon group is reduced and lipid bilayer becomes less deformable.
Ques. How cholesterol is produced in the body? (2 Marks)
Ans. Liver is the main producer of cholesterol. Cholesterol is also produced by other cells too but in less quantity. Cholesterol is also absorbed from the everyday diet, mostly from meat, poultry, eggs and milk products.
Ques. What are the functions of Cholesterol? (2 Marks)
Ans. The main function of cholesterol is to maintain cell membranes. To keep it intact and fluid. It also acts as a precursor for various essential substances such as hormones, vitamin D and bile acids.
Ques. Why is Cholesterol important? (2 Marks)
Ans. Cholesterol is found in blood plasma, body cells and in lipids. Cholesterol itself is an amphipathic lipid. It is used in the creation of cell membranes and skin barriers. It also plays an important role in producing harmouns, Vitamin D and crucial role in digestion. Cholesterol helps in production of bile acid which plays a key role in the human digestive system.
Ques. What are types of Cholesterol? (3 Marks)
Ans. Cholesterol is divided into two types based on the rate of lipoproteins.
- HDL cholesterol
HDL stands for high density lipoprotein. It is good cholesterol with HDL proteins. These proteins are efficient against heart attack and stroke. It should be in the range of 40 and above
- LDL Cholesterol
LDL stands for low density lipoproteins. It is bad cholesterol. Increase in the quantity of LDL may result in coronary heart disease, stroke and peripheral artery disease. Too much LDL in blood can block blood clots. It should be in the range of below 100.
Ques. What is a bad type of cholesterol? (3 Marks)
Ans. Cholesterol is divided into two main types based on the rate of lipoproteins. HDL cholesterol and LDL cholesterol. LDL cholesterol is known as bad cholesterol. LDL stands for Low Density Lipoproteins. As the rate of LDL increases in the body it can cause serious health problems like, coronary heart disease, stroke and peripheral artery disease.
Cholesterol also flows through blood vessels and mixes with proteins so it's called lipoproteins. If the rate of LDL increases in blood, it slowly forms plague, which ends up blocking blood flow and formation of blood clots. It can also become the cause of heart attack if the blood clots are formed near the heart.
Ques. What are risk factors of Cholesterol? (2 Marks)
Ans. Cholesterol can be influenced by various facts such as age, gender, weight, diseases, genetics and lifestyle. The basic reason for high cholesterol level is diet, also in increase in cholesterol level heredity also plays a crucial role. The increase in high density cholesterol can be caused by lack of regular exercise and might result in heart disease.
Ques. Give any five properties of Cholesterol? (2 Marks)
Ans.
| Properties | Details |
|---|---|
| Molecular Formula | C27H46O |
| Boiling point | 360ºC |
| Odour | Almost Odourless |
| Colour/ Form | White or faintly yellow pearly granules or crystals |
| Molecular mass | 386.664 g/mol |
Ques. What groups does Cholesterol belong to? [JEE 2008, Odisha] (2 Marks)
a.Waxes
b.Steroids
c. Neutral facts
d. Phospholipids
Ans. b- steroids
Explanation: Cholesterol is sterol type lipid. Cholesterol is also a precursor for various essential substances such as hormones, vitamin D and bile acids. Cholesterol is also a principal sterol in the animal body. So the option (b) Steroids.
Ques. Synthesising of Cholesterol is done in______. (2 Marks)
a.Spleen c. burner’s grand
b.Liver
c. burner’s grand
d. Pancreas
Ans. b- liver
Explanation: Cholesterol is sterol type lipid. It is important in production of vitamins D, hormones and bile acids. Everyday requirement of cholesterol is synthesis by hepatic cells. And the liver is formed by hepatic cells. So option (b) Liver.
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