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In molecular biology, a polynucleotide (from Ancient Greek πολυς (polys) 'many') is a biopolymer composed of nucleotide monomers that are covalently bonded in a chain. [1] DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are examples of polynucleotides with distinct biological functions.
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 bonds in base pairs, the stronger forces holding the two strands together are stacking interactions between the bases.
The term nucleic acid is the overall name for DNA and RNA, members of a family of biopolymers, [13] and is a type of polynucleotide. Nucleic acids were named for their initial discovery within the nucleus , and for the presence of phosphate groups (related to phosphoric acid). [ 14 ]
While canonical Watson-Crick base pairs are most prevalent and are commonly observed in a majority of chromosomal DNA and in most functional RNAs, presence of stable non-canonical base pairs is also extremely significant in DNA biology. An example of non-Watson-Crick, or non-canonical, base pairing can be found at the ends of chromosomal DNA.
In biology, parts of the DNA double helix that need to separate easily, such as the TATAAT Pribnow box in some promoters, tend to have a high AT content, making the strands easier to pull apart. [29] In the laboratory, the strength of this interaction can be measured by finding the melting temperature T m necessary to break half of the hydrogen ...
The discovery of DNA ligase dates back to 1967 and was an important event in the field of molecular biology. [1] Ligation in the laboratory is normally performed using T4 DNA ligase . It is broadly used in vitro due to its capability of joining sticky-ended fragments as well as blunt-ended fragments. [ 2 ]
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.
In molecular biology, endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain (namely DNA or RNA).Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (with regard to sequence), while many, typically called restriction endonucleases or restriction enzymes, cleave only at very specific nucleotide sequences.