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:
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Cholesterol.
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Ergosterol.
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Male and female sex hormones.
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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:
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Blood.
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Animal tissues.
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Eggs.
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Yolk.
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Various oils and fats.
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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.
