Examples of Lipids | Their Structure and Function in Biology

Lipids are macromolecules that are insoluble in water.

They are present in living organisms and are also widely distributed in nature.

Examples of lipids include

1. Oils
2. Fats
3. Waxes
4. Phospholipids
5. Sphingolipids
6. Steroids

Sl.No	Type of lipid	Lipid name	Source
1	Oils	Peanut oil (arachis oil)	Peanut or ground nut
2		Sesame oil	Sesame seeds
3		Olive oil
4	Fats	Butter	Dairy products
5		clarified butter	Dairy products
6		Margarine	Vegetable oil + water
7		Hydrogenated vegetable fat	Vegetable oil
8	Eicosanoids	Prostaglandins	The cell membrane (arachidonic acid)
9		Leukotrienes
10		Thromboxane	Cell membrane
11	Steroid	Cholesterol	Synthesized in the body.
12		Ergosterol	plants, yeast
13		Butter	Milk
14		Galactosylceramide	brain

Lipids are one of our body’s 4 significant macromolecules that are taken from an external diet.

Also, some of them are biosynthesized in our body as per need from excess carbohydrates and other sources.

Lipids vary in structure, properties, and functions in the body.

They are insoluble in water and hence called hydrophobic.

Types of Lipids

Lipids are of two types as

1. Simple lipids
2. Compound lipid.

Simple lipids

These are the ones that are esters of fatty acid and alcohol. They are again of three types as

a) Neutral fats (glycerides) 

• They have an ester of fatty acid and glycerol.

• They tend to accumulate in our bodies and contribute to weight gain.

• At room temperature, they are solid.

Example: Butter

b) Oils

• Like fats, they are also esters of fatty acid and glycerol but are liquids at room temperature.

Ex: all edible oils

c) Waxes

• These are also esters but have fatty acids linked with non-glycerol alcohol. 

• This alcohol is a high molecular weight monohydric alcohol.

Ex: Bee wax.

• The fats are stored in the body and are used in times of starvation.

These are of different types based on the fatty acid in them.

Fatty acid Structure

• Lipids are chemically the esters of long-chain fatty acids with alcohols.
• They have the following formula.

HOOC-(CH)2-CH3 fatty acids

These fatty acids are obtained from plants, animals (meat), and even minerals.

Compound lipids

• These have complex chemistry with cyclic structures or multiple functional groups.

• They are mostly involved in the formation of membranes of the body cells.

They are of different types like

1. Phospholipids
2. Sphingolipids
3. Steroids

Phospholipids

• They have phosphate groups in their chemical structure.

• The phosphate moiety determines the water-permeable nature of the membrane it forms.

• These phospholipids are mostly present in cell membranes.

In general, a cell or plasma membrane has double layers of phospholipids, as shown in the image below.

Sphingolipids

• These lipids have amine and other functional groups in their chemistry.

• Sphingomyelin is a part of the nerve cell membrane.

Steroidal lipids.

• These lipids are formed inside the body and sometimes are taken from external sources.

• They have a cyclic ring-like structure in their chemistry, due to which they are called steroids.

• These steroids, like cholesterol, are chemical constituents of the cell membrane.

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