DNA Polymerase Joins Nucleotides via Phosphodiester Bonds

Steps:

• DNA replication involves adding deoxynucleoside triphosphates (dNTPs, nucleotides) to the 3' end of the growing DNA strand.
• The condensation reaction forms a phosphodiester bond by linking the 5' phosphate of the incoming nucleotide to the 3' hydroxyl group of the deoxyribose sugar on the previous unit.
• The previous unit's end functions as a nucleoside (base + sugar) after phosphate release.
• Thus, DNA polymerase joins a nucleotide to the nucleoside at the chain's 3' end.

Why C is correct:

• Nucleotides (base + sugar + phosphate) are the monomers added; the 3' end acts as a nucleoside (base + sugar), matching the definition of DNA polymerization.

Why the others are wrong:

• A: Bases are not directly joined; they pair via hydrogen bonds, not condensation.
• B: Bases are components, not standalone molecules joined by polymerase.
• D: Phosphate and deoxyribose form nucleotides but are not the primary molecules linked in replication.

Final answer: C