How are the two strands of nucleic acid in DNA held together?

Verified step by step guidance

1. Identify the two strands of nucleic acid in DNA as polynucleotide chains composed of nucleotides.
2. Understand that each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
3. Recognize that the two strands are held together by hydrogen bonds between complementary nitrogenous bases.
4. Note that adenine (A) pairs with thymine (T) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds.
5. Acknowledge that these hydrogen bonds create the double helix structure of DNA, providing stability and specificity in base pairing.

Key Concepts

Base Pairing

Base pairing is the fundamental mechanism by which the two strands of DNA are held together. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G) through hydrogen bonds. This specific pairing ensures the stability of the double helix structure and allows for accurate replication and transcription of genetic information.

Hydrogen Bonds

Hydrogen bonds are weak interactions that occur between the nitrogenous bases of the two DNA strands. Each base pair is connected by hydrogen bonds, with A-T pairs forming two hydrogen bonds and C-G pairs forming three. Although individually weak, the cumulative effect of many hydrogen bonds contributes significantly to the overall stability of the DNA molecule.

Double Helix Structure

The double helix structure of DNA refers to its twisted ladder-like shape, formed by two long strands of nucleotides running in opposite directions. This configuration not only protects the genetic information but also facilitates the processes of replication and transcription. The helical shape is stabilized by the interactions between the base pairs and the sugar-phosphate backbone of the strands.