Final answer:
B. phosphodiester bonds. The type of bond that links two polynucleotide chains in a double helix of DNA is phosphodiester bonds. These bonds are formed through a dehydration synthesis reaction between nucleotides, creating the backbone of the DNA molecule. Hydrogen bonds between complementary bases hold the nitrogenous bases together, forming the rungs of the DNA double helix.
Step-by-step explanation:
The type of bond that links two polynucleotide chains to each other in a double helix of DNA is phosphodiester bonds.
Phosphodiester bonds are a type of covalent bond that forms between nucleotides in DNA. They are formed through a dehydration synthesis reaction, where a hydroxyl group is removed from the 3' carbon of one nucleotide and a hydrogen atom is removed from the hydroxyl group attached to the 5' carbon of another nucleotide. This process creates a phosphodiester bond and releases a water molecule.
These phosphodiester bonds create the backbone of the DNA molecule, which consists of alternating sugar (deoxyribose) and phosphate groups. The nitrogenous bases, adenine (A), thymine (T), cytosine (C), and guanine (G), are held together by hydrogen bonds between complementary bases, forming the rungs of the DNA double helix.