Lipids:

• Lipids are a diverse group of hydrophobic organic molecules.
• They include fats, oils, phospholipids, steroids, and waxes.
• Lipids serve various functions in living organisms, including energy storage, insulation, cell membrane structure, and signaling.
• Fats and oils, composed of triglycerides, are common energy storage molecules in animals and plants.

Types of Lipids:

1. Triglycerides: Composed of glycerol and three fatty acid chains, they serve as a primary energy storage form in organisms.

2. Phospholipids: Important components of cell membranes, featuring hydrophilic phosphate heads and hydrophobic fatty acid tails.

3. Steroids: Include molecules like cholesterol and hormones such as estrogen and testosterone, playing roles in membrane structure and signaling.

4. Waxes: Long-chain fatty acids linked to long-chain alcohols; they provide waterproofing in plants and animals.

Nitrogenous Bases and Nucleic Acid Introduction:

• Nitrogenous bases are the building blocks of nucleic acids, DNA (deoxyribonucleic acid), and RNA (ribonucleic acid).

• Nucleic acids are essential for the storage and transmission of genetic information in living organisms.

• DNA contains the genetic instructions necessary for development, functioning, and reproduction, while RNA plays a key role in protein synthesis.

• Nitrogenous bases in DNA include adenine (A), cytosine (C), guanine (G), and thymine (T), while RNA replaces thymine with uracil (U).

• Base pairing rules, such as A pairing with T (or U in RNA) and C pairing with G, dictate the complementary structure of DNA strands and RNA molecules.