Steroids structure | Cholesterol, Ergosterol |

Steroids.

Steroids are basically lipids that are naturally occurring.

Structure of Steroids:

The parent nucleus of steroids has consisted of four rings. Three rings are six-membered and the fourth one is five-membered.

The parent nucleus has perhydrocyclopentanophenanthrene component.

These rings are fused with each other and have a total of seventeen carbon atoms.

Different types of groups can be attached to these rings. Even a small variation in the bonding of the atoms in the rings and the groups attached to the changes the properties of steroids to a great extent. There happens a diverse in their biological functions.

Some of the important steroids are followed:

1. Cholesterol.
2. Ergosterol.
3. Male and female sex hormones.
4. Hormones of the adrenal cortex.

Cholesterol.

It is one of the most abundant animal steroids. It occurs in all the animals is but in a few higher plants.

Cholesterol is present in both free as well as in esterified form in:

1. Blood.
2. Animal tissues.
3. Eggs.
4. Yolk.
5. Various oils and fats.
6. Nerve tissues.

Side Effects:

When the cholesterol deposits are increased in the blood, then it causes blood pressure and other heart diseases.

Structure:

The structure of cholesterol is given as follows:

Ergosterol:

It is a sterol of fungi and yeast. When it is exposed to U.V. radiations, it is converted to ergocalciferol or vitamin D.

Phospholipids:

These molecules are of enormous biological importance. In these compounds, two of the - OH groups are esterified with a fatty acid. The third -OH group forms a link with H3PO4 or a derivative of H3PO4.