Base pair

A base pair (bp) is a unit consisting of two nucleobases bound to each other by hydrogen bonds.

The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).

They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA.

The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA.

The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and RNA polymerase transcribes DNA into RNA.

Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form, in the process breaking the hydrogen bonds between the nucleotide bases.

This is particularly important in RNA molecules (e.g., transfer RNA), where Watson–Crick base pairs (guanine–cytosine and adenine–uracil) permit the formation of short double-stranded helices, and a wide variety of non-Watson–Crick interactions (e.g., G–U or A–A) allow RNAs to fold into a vast range of specific three-dimensional structures. In addition, base-pairing between transfer RNA (tRNA) and messenger RNA (mRNA) forms the basis for the molecular recognition events that result in the nucleotide sequence of mRNA becoming translated into the amino acid sequence of proteins via the genetic code.

The anticodon forms three complementary base pairs with a codon in mRNA during protein biosynthesis.

Dictated by specific hydrogen bonding patterns, Watson–Crick base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The complementary nature of this based-paired structure provides a redundant copy of the genetic information encoded within each strand of DNA.

The nucleobases are important in base pairing of strands to form higher-level secondary and tertiary structure such as the famed double helix.

The complementary nature of this based-paired structure provides a redundant copy of the genetic information encoded within each strand of DNA.

The degree of complementarity between two nucleic acid strands may vary, from complete complementarity (each nucleotide is across from its opposite) to no complementarity (each nucleotide is not across from its opposite) and determines the stability of the sequences to be together.

Hence, the number of total base pairs is equal to the number of nucleotides in one of the strands (with the exception of non-coding single-stranded regions of telomeres).

In humans, average telomere length declines from about 11 kilobases at birth to fewer than 4 kilobases in old age, with the average rate of decline being greater in men than in women.

Dictated by specific hydrogen bonding patterns, Watson–Crick base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence.

In Watson-Crick base pairing, it forms three hydrogen bonds with guanine.

This is particularly important in RNA molecules (e.g., transfer RNA), where Watson–Crick base pairs (guanine–cytosine and adenine–uracil) permit the formation of short double-stranded helices, and a wide variety of non-Watson–Crick interactions (e.g., G–U or A–A) allow RNAs to fold into a vast range of specific three-dimensional structures.

In RNA, uracil base-pairs with adenine and replaces thymine during DNA transcription.

The haploid human genome (23 chromosomes) is estimated to be about 3.2 billion bases long and to contain 20,000–25,000 distinct protein-coding genes.

Haploid human genomes, which are contained in germ cells (the egg and sperm gamete cells created in the meiosis phase of sexual reproduction before fertilization creates a zygote) consist of three billion DNA base pairs, while diploid genomes (found in somatic cells) have twice the DNA content.

A base pair (bp) is a unit consisting of two nucleobases bound to each other by hydrogen bonds. Dictated by specific hydrogen bonding patterns, Watson–Crick base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence.

For example, the double helical structure of DNA is due largely to hydrogen bonding between its base pairs (as well as pi stacking interactions), which link one complementary strand to the other and enable replication.

They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. The GU pairing, with two hydrogen bonds, does occur fairly often in RNA (see wobble base pair).

This antisense-based process involves steps that first process the RNA so that it can base-pair with a region of its target mRNAs.

In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).

The total number of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at (5.3±3.6), and weighs 50 billion tonnes.

In addition, base-pairing between transfer RNA (tRNA) and messenger RNA (mRNA) forms the basis for the molecular recognition events that result in the nucleotide sequence of mRNA becoming translated into the amino acid sequence of proteins via the genetic code.

The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodon located on a transfer RNA molecule, which carries the amino acid corresponding to the codon it recognizes.

The haploid human genome (23 chromosomes) is estimated to be about 3.2 billion bases long and to contain 20,000–25,000 distinct protein-coding genes.

The chromosomes of most bacteria, which some authors prefer to call genophores, can range in size from only 130,000 base pairs in the endosymbiotic bacteria Candidatus Hodgkinia cicadicola and Candidatus Tremblaya princeps, to more than 14,000,000 base pairs in the soil-dwelling bacterium Sorangium cellulosum.

The size of an individual gene or an organism's entire genome is often measured in base pairs because DNA is usually double-stranded.

Two chains of DNA twist around each other to form a DNA double helix with the phosphate-sugar backbone spiralling around the outside, and the bases pointing inwards with adenine base pairing to thymine and guanine to cytosine.

The GU pairing, with two hydrogen bonds, does occur fairly often in RNA (see wobble base pair).

A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules.

This is particularly important in RNA molecules (e.g., transfer RNA), where Watson–Crick base pairs (guanine–cytosine and adenine–uracil) permit the formation of short double-stranded helices, and a wide variety of non-Watson–Crick interactions (e.g., G–U or A–A) allow RNAs to fold into a vast range of specific three-dimensional structures.

The nucleotides on one strand base pairs with the nucleotide on the other strand.

On the converse, regions of a genome that need to separate frequently — for example, the promoter regions for often-transcribed genes — are comparatively GC-poor (for example, see TATA box). Chemical analogs of nucleotides can take the place of proper nucleotides and establish non-canonical base-pairing, leading to errors (mostly point mutations) in DNA replication and DNA transcription.

Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language.

On the converse, regions of a genome that need to separate frequently — for example, the promoter regions for often-transcribed genes — are comparatively GC-poor (for example, see TATA box).

It was termed the "TATA box" as it contains a consensus sequence characterized by repeating T and A base pairs.

DNA with high GC-content is more stable than DNA with low GC-content.

Quantitatively, each GC base pair is held together by three hydrogen bonds, while AT and AU base pairs are held together by two hydrogen bonds.

By convention, the top strand is written from the 5' end to the 3' end; thus, the bottom strand is written 3' to 5'.

In a DNA double helix, the strands run in opposite directions to permit base pairing between them, which is essential for replication or transcription of the encoded information.

Chemical analogs of nucleotides can take the place of proper nucleotides and establish non-canonical base-pairing, leading to errors (mostly point mutations) in DNA replication and DNA transcription.

Nucleobases are matched between strands through hydrogen bonds to form base pairs.

GC content and melting temperature must also be taken into account when designing primers for PCR reactions.

In solution, the primer spontaneously hybridizes with the template through Watson-Crick base pairing before being extended by DNA polymerase.

GC content and melting temperature must also be taken into account when designing primers for PCR reactions.

Most PCR methods amplify DNA fragments of between 0.1 and 10 kilo base pairs (kbp) in length, although some techniques allow for amplification of fragments up to 40 kbp.