Which type of bond is formed between nucleotides during the synthesis of a new DNA strand?

• A. Phosphodiester bonds
• B. Disulfide bonds
• C. Peptide bonds
• D. Hydrogen bonds

Answer: (A)

Verified step by step guidance

1. Understand the structure of nucleotides: Nucleotides consist of three components—a phosphate group, a sugar (deoxyribose in DNA), and a nitrogenous base. During DNA synthesis, these nucleotides are linked together to form a strand.
2. Identify the type of bond formed between nucleotides: During DNA synthesis, the phosphate group of one nucleotide forms a bond with the hydroxyl group on the 3' carbon of the sugar in the previous nucleotide. This bond is known as a phosphodiester bond.
3. Clarify the role of phosphodiester bonds: Phosphodiester bonds create the backbone of the DNA strand, connecting the sugar of one nucleotide to the phosphate group of the next nucleotide. This bond is essential for the structural integrity of the DNA molecule.
4. Differentiate from other bond types: Disulfide bonds are covalent bonds between sulfur atoms in cysteine residues (important in protein structure). Peptide bonds link amino acids in proteins. Hydrogen bonds occur between complementary nitrogenous bases in DNA but do not form the backbone of the strand.
5. Conclude the answer: The correct bond type formed between nucleotides during DNA synthesis is the phosphodiester bond, as it links the sugar-phosphate backbone of the DNA strand.