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The chemical structure of DNA base-pairs . A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA.
These purine-pyrimidine pairs, which are called base complements, connect the two strands of the helix and are often compared to the rungs of a ladder. Only pairing purine with pyrimidine ensures a constant width for the DNA. The A–T pairing is based on two hydrogen bonds, while the C–G pairing is based
A purine base always pairs with a pyrimidine base (guanine (G) pairs with cytosine (C) and adenine (A) pairs with thymine (T) or uracil (U)). DNA's secondary structure is predominantly determined by base-pairing of the two polynucleotide strands wrapped around each other to form a double helix. Although the two strands are aligned by hydrogen ...
A complementary strand of DNA or RNA may be constructed based on nucleobase complementarity. [2] Each base pair, A = T vs. G ≡ C, takes up roughly the same space, thereby enabling a twisted DNA double helix formation without any spatial distortions. Hydrogen bonding between the nucleobases also stabilizes the DNA double helix. [3]
The double helical structures of DNA or RNA are generally known to have base pairs between complementary bases, Adenine:Thymine (Adenine:Uracil in RNA) or Guanine:Cytosine. They involve specific hydrogen bonding patterns corresponding to their respective Watson-Crick edges, and are considered as Canonical Base Pairs.
In the canonical Watson-Crick base pairing, adenine (A) forms a base pair with thymine (T) and guanine (G) forms one with cytosine (C) in DNA. In RNA, thymine is replaced by uracil (U). Alternate hydrogen bonding patterns, such as the wobble base pair and Hoogsteen base pair, also occur—particularly in RNA—giving rise to complex and ...
This RNA copy is then decoded by a ribosome that reads the RNA sequence by base-pairing the messenger RNA to transfer RNA, which carries amino acids. Since there are 4 bases in 3-letter combinations, there are 64 possible codons (4 3 combinations).
Thymine occurs only in DNA and uracil only in RNA. Using amino acids and protein synthesis, [2] the specific sequence in DNA of these nucleobase-pairs helps to keep and send coded instructions as genes. In RNA, base-pair sequencing helps to make new proteins that determine most chemical processes of all life forms.