MPSC Notes - Fat Review - Lipids (Parts- I)

 Fat Review - Lipids

1. What are the main types of lipids?

The main types of lipids are triglycerides (fats and oils), phospholipids, waxes and steroids.

2. What is the structural formula of glycerol? To which organic function do these molecules belong?

Glycerol is a linear chain of three carbons; the central carbon is bound to one hydroxyl radical and to one hydrogen and the two other carbons in the extremities are bound to a hydroxyl radical and to two hydrogens. Spatial sides of the hydroxyls are the same.

3. How are triglycerides made?

Triglycerides, fats or oils, are made of three molecules of fatty acids bound to one molecule of glycerol. Hydroxyls of each one of the three fatty acids and each hydrogen of the hydroxyls of the glycerol bind to form three molecules of water that are liberated.

4. What are phospholipids?

Phospholipids are molecules made of glycerol bound to two long molecules of fatty acids and to one phosphate group. Therefore, phospholipids are amphipathic molecules, i.e., they have a non-polar portion, due to the long fatty acid chains, and a polar portion, due to the group phosphate.

Phospholipids are the main component of cell membranes. Sphingomyelin, the substance that forms the myelin sheath of axons in the nervous system, is a phospholipid too.

5. What are steroids? What are some examples of steroids with a biological function?

Steroids are lipids based in an angular combination of four carbon rings, three of them made of six carbons and one ring made of five carbons in the extremity. The union of each ring to the adjacent ring is made by the sharing of two adjacent carbons belonging to both rings.

Bile salts, cholesterol, the sexual hormones estrogen, progesterone and testosterone, the corticosteroids and the pro-vitamin D are examples of steroids.

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