Draw a schematic diagram of a part of double-stranded dinucleotide DNA chain having all four nitrogenous bases and showing the correct polarity.

A schematic diagram of a part of a double-stranded dinucleotide DNA chain showing all four nitrogenous bases and correct polarity would look something like this:

          5'                                      3'
          |                                      |
     P-A-T-G-C-P                             P-T-A-C-G-P
          |                                      |
          3'                                      5'

     Where:
     * P represents the phosphate group.
     * A represents adenine.
     * T represents thymine.
     * G represents guanine.
     * C represents cytosine.
     * The numbers (5' and 3') indicate the directionality of the DNA strands.  The 5' end has a free phosphate group, and the 3' end has a free hydroxyl group.

     Adenine (A) always pairs with Thymine (T) via two hydrogen bonds, and Guanine (G) always pairs with Cytosine (C) via three hydrogen bonds.  This is base pairing. The diagram depicts this base pairing and the antiparallel nature of the DNA strands (one strand running 5' to 3', the other 3' to 5').

Detailed Explanation:

The DNA double helix consists of two polynucleotide strands running antiparallel to each other. Each nucleotide is composed of a deoxyribose sugar, a phosphate group, and one of the four nitrogenous bases (adenine, guanine, cytosine, or thymine). The phosphate group connects the 3' carbon of one sugar to the 5' carbon of the next sugar, creating the sugar-phosphate backbone. The nitrogenous bases are paired in the center of the helix, forming hydrogen bonds between A-T and G-C base pairs. The 5' to 3' polarity of each strand refers to the orientation of the sugar-phosphate backbone. The 5' end of a strand has a free phosphate group, while the 3' end has a free hydroxyl group.