In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and which of the following atoms or molecules of the last nucleotide in the DNA strand?

• A. The 5' phosphate group.
• B. C6.
• C. The 3' OH.
• D. A nitrogen from the nitrogen-containing base.

Answer: (C)

Verified step by step guidance

1. Understand the structure of a nucleotide: A nucleotide consists of a phosphate group, a sugar molecule (deoxyribose in DNA), and a nitrogenous base.
2. Identify the ends of a DNA strand: DNA strands have directionality, with a 5' end and a 3' end. The 5' end has a phosphate group, and the 3' end has a hydroxyl group (OH) attached to the sugar.
3. Recognize the process of DNA polymerization: During DNA synthesis, nucleotides are added to the growing DNA strand. This involves forming a phosphodiester bond between the incoming nucleotide and the existing strand.
4. Determine the site of bond formation: The phosphodiester bond is formed between the phosphate group of the incoming nucleotide and the 3' hydroxyl group (OH) of the last nucleotide in the DNA strand.
5. Visualize the chemical reaction: The reaction involves the nucleophilic attack of the 3' OH group on the alpha phosphate of the incoming nucleotide, releasing pyrophosphate and forming the phosphodiester linkage.