Final answer:
The nitrogenous bases from opposing strands of DNA are linked by hydrogen bonds. Adenine pairs with thymine and forms two hydrogen bonds, while cytosine pairs with guanine and forms three hydrogen bonds, maintaining the uniform helical shape of DNA.
Step-by-step explanation:
The nitrogenous bases from opposing strands of DNA are linked together by hydrogen bonds. The four nitrogenous bases—adenine (A), thymine (T), cytosine (C), and guanine (G)—pair with each other in a specific pattern: adenine with thymine, and cytosine with guanine. These base pairings are known as complementary base pairs.
Each base pair is connected by hydrogen bonds, which are relatively weak interactions that can be easily disrupted by heat or chemicals. However, collectively, they provide stability to the DNA molecule's structure. Adenine and thymine form two hydrogen bonds between them, while cytosine and guanine form three. The antiparallel orientation of the two DNA strands—one running 3' to 5' and the other 5' to 3'—facilitates this specific bonding.
The hydrogen bonds ensure the DNA double helix has a consistent width, allowing the molecule to maintain its uniform helical shape. This what keeps the double helix structure of DNA stable and allows for the accurate transmission of genetic information during cell division and the synthesis of RNA and proteins.