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Unlike double-stranded DNA, RNA is usually a single-stranded molecule (ssRNA) [4] in many of its biological roles and consists of much shorter chains of nucleotides. [5] However, double-stranded RNA (dsRNA) can form and (moreover) a single RNA molecule can, by complementary base pairing, form intrastrand double helixes, as in tRNA.
In most cases, naturally occurring DNA molecules are double-stranded and RNA molecules are single-stranded. [19] There are numerous exceptions, however—some viruses have genomes made of double-stranded RNA and other viruses have single-stranded DNA genomes, [20] and, in some circumstances, nucleic acid structures with three or four strands ...
An individual strand of DNA is referred to as positive-sense (also positive (+) or simply sense) if its nucleotide sequence corresponds directly to the sequence of an RNA transcript which is translated or translatable into a sequence of amino acids (provided that any thymine bases in the DNA sequence are replaced with uracil bases in the RNA ...
Double-stranded RNA forms an A-type helical structure, unlike the common B-type conformation taken by double-stranded DNA molecules. The secondary structure of RNA consists of a single polynucleotide. Base pairing in RNA occurs when RNA folds between complementarity regions. Both single- and double-stranded regions are often found in RNA molecules.
The sequence of nucleobases on a nucleic acid strand is translated by cell machinery into a sequence of amino acids making up a protein strand. Each group of three bases, called a codon , corresponds to a single amino acid, and there is a specific genetic code by which each possible combination of three bases corresponds to a specific amino acid.
Here, the single-stranded DNA curls around in a long circle stabilized by telomere-binding proteins. [68] At the very end of the T-loop, the single-stranded telomere DNA is held onto a region of double-stranded DNA by the telomere strand disrupting the double-helical DNA and base pairing to one of the two strands.
In a double stranded nucleic acid, an additional three reading frames may be read from the other, complementary strand in the 5′→3′ direction along this strand. As the two strands of a double-stranded nucleic acid molecule are antiparallel, the 5′→3′ direction on the second strand corresponds to the 3′→5′ direction along the ...
It is similar to DNA but with the replacement of thymine by uracil and the adding of one oxygen atom. [1] Despite the structural similarities, much less is known about dsRNA. [2] They form the genetic material of some viruses (double-stranded RNA viruses). dsRNA, such as viral RNA or siRNA, can trigger RNA interference in eukaryotes, as well as ...