Question

Kindly answer all the following questions please!

1. What makes a lipid complex and simple? What is the basis of this classification?

2. In every classification of lipids, kindly cite at least 3 example each and provide their essential role.

Answer 1

1- Simple lipids are esters of fatty acids with various alcohols. For eg., fats and waxes. On the contrary, complex lipidsare esters of fatty acids with groups other than alcohol and fatty acids. For eg., phospholipids and sphingolipids.

According to the chosen classification, they contain frequently three or more chemical identities (i.e. glycerol, fatty acids and sugar, one long chain base, one nucleoside, one fatty acid and one phosphate group. and have polar properties. Some contain only two components but including a sugar moiety.

A lipid is a type of organic molecule found in living things. It is oily or waxy. Fats are made from lipid molecules. ... Lipids are long chains of carbon and hydrogen molecules. Lipids are classified as simple and complex.

A saponifiable lipid comprises one or more ester groups, enabling it to undergo hydrolysis in the presence of a base, acid, or enzymes, including waxes, triglycerides, sphingolipids, and phospholipids. Further, these categories can be divided into non-polar and polar lipids.

Based on this classification system, lipids have been divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids and polyketides (derived from condensation of ketoacyl subunits) and sterol lipids and prenol lipids (derived from condensation of isoprene subunits)

2-

What are Lipids?

These organic compounds are nonpolar molecules, which are soluble only in nonpolar solvents and insoluble in water because water is a polar molecule. In the human body, these molecules can be synthesized in the liver and are found in oil, butter, whole milk, cheese, fried foods, and also in some red meats.

Classification of Lipids-

Lipids can be classified into two main classes:

• Nonsaponifiable lipids, and
• Saponifiable lipids.

Nonsaponifiable Lipids

A nonsaponifiable lipid cannot be disintegrated into smaller molecules through hydrolysis. Nonsaponifiable lipids include cholesterol, prostaglandins etc

Saponifiable Lipids

A saponifiable lipid comprises one or more ester groups, enabling it to undergo hydrolysis in the presence of a base, acid, or enzymes, including waxes, triglycerides, sphingolipids, and phospholipids.

Further, these categories can be divided into non-polar and polar lipids.

Nonpolar lipids, namely triglycerides, are utilized as fuel and to store energy.

Polar lipids, that could form a barrier with an external water environment, are utilized in membranes. Polar lipids comprise sphingolipids and glycerophospholipids.

Fatty acids are pivotal components of all these lipids.

Types of Lipids-

Within these two major classes of lipids, there are numerous specific types of lipids important to live, including fatty acids, triglycerides, glycerophospholipids, sphingolipids, and steroids. These are broadly classified as simple lipids and complex lipids.

Simple Lipids

Esters of fatty acids with various alcohols.

1. Fats: Esters of fatty acids with glycerol. Oils are fats in the liquid state

1. Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols

Complex Lipids

Esters of fatty acids containing groups in addition to alcohol and a fatty acid.

1. Phospholipids: These are lipids containing, in addition to fatty acids and alcohol, a phosphoric acid residue. They frequently have nitrogen-containing bases and other substituents, eg, in glycerophospholipids the alcohol is glycerol and in sphingophospholipids the alcohol is sphingosine.

1. Glycolipids (glycosphingolipids): Lipids containing a fatty acid, sphingosine, and carbohydrate.

1. Other complex lipids: Lipids such as sulfolipids and amino lipids. Lipoproteins may also be placed in this category

Precursor and Derived Lipids

These include fatty acids, glycerol, steroids, other alcohols, fatty aldehydes, and ketone bodies, hydrocarbons, lipid-soluble vitamins, and hormones. Because they are uncharged, acylglycerols (glycerides), cholesterol, and cholesteryl esters are termed neutral lipids. These compounds are produced by the hydrolysis of simple and complex lipids.

Some of the different types of lipids are described below in detail.

Fatty Acids

Fatty acids are carboxylic acids (or organic acid), usually with long aliphatic tails (long chains), either unsaturated or saturated.

• Saturated fatty acids

Lack of carbon-carbon double bonds indicates that the fatty acid is saturated. The saturated fatty acids have higher melting points compared to unsaturated acids of the corresponding size due to their ability to pack their molecules together thus leading to a straight rod-like shape.

• Unsaturated fatty acids

Unsaturated fatty acid is indicated when a fatty acid has more than one double bond.

“Often, naturally occurring fatty acids possesses an even number of carbon atoms and are unbranched.”

On the other hand, unsaturated fatty acids contain a cis-double bond which create a structural kink that disables them to group their molecules in straight rod-like shape.

Role of Fats-

Fats play several major roles in our body. Some of the important roles of fats are mentioned below:

• Fats in the correct amounts are necessary for the proper functioning of our body.
• Many fat-soluble vitamins need to be associated with fats in order to be effectively absorbed by the body.
• They also provide insulation to the body.
• They are an efficient way to store energy for longer periods.

Waxes

Waxes are “esters” (an organic compound made by replacing the hydrogen with acid by an alkyl or another organic group) formed from long-alcohols and long-chain carboxylic acids.

Waxes are found almost everywhere. Fruits and leaves of many plants possess waxy coatings, that can safeguard them from small predators and dehydration.

Fur of a few animals and the feathers of birds possess same coatings serving as water repellants.

Carnauba wax is known for its water resistance and toughness.

Cholesterol

• Cholesterol is a wax-like substance, found only in animal source foods. Triglycerides, LDL, HDL, VLDL are different types of cholesterol found in the blood cells.
• Cholesterol is an important lipid found in the cell membrane. It is a sterol, which means that cholesterol is a combination of steroid and alcohol. In the human body, cholesterol is synthesized in the liver.
• These compounds are biosynthesized by all living cells and are essential for the structural component of the cell membrane.
• In the cell membrane, the steroid ring structure of cholesterol provides a rigid hydrophobic structure that helps boost the rigidity of the cell membrane. Without cholesterol, the cell membrane would be too fluid.
• It is an important component of cell membranes and is also the basis for the synthesis of other steroids, including the sex hormones estradiol and testosterone, as well as other steroids such as cortisone and vitamin D.

Examples of Lipids-

There are different types of lipids. Some examples of lipids include butter, ghee, vegetable oil, cheese, cholesterol and other steroids, waxes, phospholipids, and fat-soluble vitamins. All these compounds have similar features, i.e. insoluble in water and soluble in organic solvents, etc.