For the following fragment of DNA, determine the number of hydrogen bonds and the number of phosphodiester bonds present:

5'-ACGTAGAGTGCTC-3'
3'-TGCATCTCACGAG-5'

Key Concepts

Hydrogen Bonds

Hydrogen bonds are weak interactions that occur between complementary nitrogenous bases in DNA. In the double helix structure, adenine (A) pairs with thymine (T) through two hydrogen bonds, while cytosine (C) pairs with guanine (G) through three hydrogen bonds. Understanding the number of hydrogen bonds is crucial for determining the stability and structure of the DNA molecule.

Phosphodiester Bonds

Phosphodiester bonds are covalent linkages that connect the sugar and phosphate groups in the backbone of a DNA strand. Each bond forms between the 3' hydroxyl group of one nucleotide and the 5' phosphate group of the next, creating a continuous sugar-phosphate backbone. Recognizing the number of phosphodiester bonds is essential for understanding the overall structure and integrity of the DNA molecule.

Complementary Base Pairing

Complementary base pairing refers to the specific pairing of nitrogenous bases in DNA, where adenine pairs with thymine and cytosine pairs with guanine. This principle is fundamental to DNA replication and transcription, as it ensures accurate copying of genetic information. Identifying the pairs in a given DNA sequence is necessary for calculating the number of hydrogen bonds.