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Nucleic acid structure refers to the structure of nucleic acids such as DNA and RNA. Chemically speaking, DNA and RNA are very similar. Chemically speaking, DNA and RNA are very similar. Nucleic acid structure is often divided into four different levels: primary, secondary, tertiary, and quaternary.
The double helix is the dominant tertiary structure for biological DNA, and is also a possible structure for RNA. Three DNA conformations are believed to be found in nature, A-DNA, B-DNA, and Z-DNA. The "B" form described by James D. Watson and Francis Crick is believed to predominate in cells. [2]
RNA-dependent DNA polymerases are a specialized class of polymerases that copy the sequence of an RNA strand into DNA. They include reverse transcriptase , which is a viral enzyme involved in the infection of cells by retroviruses , and telomerase , which is required for the replication of telomeres.
The primary structure of a biopolymer is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry).For a typical unbranched, un-crosslinked biopolymer (such as a molecule of a typical intracellular protein, or of DNA or RNA), the primary structure is equivalent to specifying the sequence of its monomeric subunits, such as amino ...
The chemical structure of RNA is very similar to that of DNA, but differs in three primary ways: 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]
In molecular biology and genetics, upstream and downstream both refer to relative positions of genetic code in DNA or RNA. Each strand of DNA or RNA has a 5' end and a 3' end, so named for the carbon position on the deoxyribose (or ribose) ring. By convention, upstream and downstream relate to the 5' to 3' direction respectively in which RNA ...
All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. [15] The basic component of biological nucleic acids is the nucleotide, each of which contains a pentose sugar (ribose or deoxyribose), a phosphate group, and a nucleobase. [16]
Nuclear DNA is a nucleic acid, a polymeric biomolecule or biopolymer, found in the nucleus of eukaryotic cells.Its structure is a double helix, with two strands wound around each other, a structure first described by Francis Crick and James D. Watson (1953) using data collected by Rosalind Franklin.