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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.
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 ...
Structural biology is the study of the structural properties of biopolymers. In contrast, most synthetic polymers have much simpler and more random (or stochastic) structures. This fact leads to a molecular mass distribution that is missing in biopolymers.
Other advances in molecular biology stemming from the discovery of the DNA double helix eventually led to ways to sequence genes. James Watson directed the Human Genome Project at the National Institutes of Health. [7] The ability to sequence and manipulate DNA is now central to the biotechnology industry and modern medicine.
This nucleotide contains the five-carbon sugar deoxyribose (at center), a nucleobase called adenine (upper right), and one phosphate group (left). The deoxyribose sugar joined only to the nitrogenous base forms a Deoxyribonucleoside called deoxyadenosine, whereas the whole structure along with the phosphate group is a nucleotide, a constituent of DNA with the name deoxyadenosine monophosphate.
The upper DNA molecule differs from the lower DNA molecule at a single base-pair location (a G/A polymorphism) In genetics and bioinformatics, a single-nucleotide polymorphism (SNP / s n ɪ p /; plural SNPs / s n ɪ p s /) is a germline substitution of a single nucleotide at a specific position in the genome.
DNA has an antiparallel, double helix structure composed of two, complementary polynucleotide strands, held together by hydrogen bonds between the base pairs. The helicase disrupts the hydrogen bonds causing a region of DNA – corresponding to a gene – to unwind, separating the two DNA strands and exposing a series of bases.