DNA is a double-stranded molecule.
DNA, or deoxyribonucleic acid, is characterized by its iconic double helix structure. This means that it's composed of two strands that are intertwined around each other, resembling a twisted ladder. Each strand is a polymer made up of nucleotides, which consist of a sugar (deoxyribose), a phosphate group, and a nitrogenous base. The nitrogenous bases are adenine (A), guanine (G), cytosine (C), and thymine (T).
The two strands are held together by hydrogen bonds that form between specific base pairs: adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). This complementary base pairing is crucial for DNA replication and transcription.
Because DNA is double-stranded, it provides a mechanism for faithful replication. Each strand serves as a template for the synthesis of a new complementary strand, ensuring that the genetic information is accurately copied and passed on to daughter cells. This also allows for DNA to have inherent redundancy. If one strand is damaged, the other strand can be used to repair it, maintaining the integrity of the genetic code.
The reference highlights that because DNA is double-stranded, two different RNA molecules could be transcribed from a single gene. Each DNA strand could theoretically serve as a template. However, in reality, only one strand is typically used as the template for transcription. This is determined by the promoter region, which signals where transcription should begin and which strand should be read.
In summary, DNA's double-stranded nature is fundamental to its function as the carrier of genetic information, enabling accurate replication and transcription.
