Watson-Crick base pairing rules

The processes of DNA and RNA synthesis are similar in that they involve (1) the general steps of initiation, elongation, and termination with y to 3 polarity (2) large, multicomponent initiation complexes and (3) adherence to Watson-Crick base-pairing rules. These processes differ in several important ways, including the... 

Here kf and kb do not have solely their usual meanings as forward and backward chemical rate constants, because the free monomer concentration has been included as a factor in kf and the concentrations of the byproducts of the forward reaction (inorganic pyrophosphate and water) have been absorbed into kb. Since there are actually four different types of monomer, each template site specifying, according to the Watson-Crick base-pairing rules, which type is to be incorporated at that site, this use of the same kf for each step is strictly valid only if all four monomer concentrations are equal, as well as essentially invariant during the duration of the process, and if the true rate constant for the incorporation of each type of monomer is independent not only of the nature of the monomer to be added but also of the nature of the sequence already incorporated. 

C) Follows Watson-Crick base pair rules... 

There are a few crystal structures containing analogues. Homo-DNA (114) is a 4 -6 -linked glucopyranosyl nucleoside that does not obey the normal Watson-Crick base pairing rules. Homo-DNA preferentially forms the following base pairs GC >... 

As confirmed by the Watson—Crick base pairing rule, the base composition of a nucleic acid follows Chargaff s rule for double-stranded DNAs, the total number of pyrimidine bases is equal to that of purine bases. In terms of mole fraction (x), Xa = Xt, Xg = Cc, and consequently Xq+c = 1 - ( Ca+t)-... 

Bases do not always pair according to the Watson—Crick base pairing rule. There are a variety of alternative H-bonded base pairing arrangements called non-Watson—Crick or wobble base pairs. Wobble base pairs occur at a high... 

L Major forces contributing to DNA conformations. The spontaneous formation of double-stranded DNA or RNA is attributed to two major forces (20,40). One is the H-bonding between complementary bases according to the Watson— Crick and non-Watson—Crick base pairing rules (sec Section II,A,2, this chapter). 

This is consistent with there not being enough space (20 °) for two purines to fit within the helix and too much space for two pyrimidines to get close enough to each other to form hydrogen bonds between them. These relationships are often called the rules of Watson-Crick base pairing. 

Fig. 3.2 Pairing rules for polyamide recognition of all four Watson—Crick base pairs of DNA. Putative hydrogen bonds are shown as dashed lines. Circles with dots represent lone pairs of N(3) of purines and 0(2) of pyrimi-...

RNA and DNA are held together by the conventional Watson-Crick base pairing hydrogen bonding rules. There is no covalent bond. 

Classic Watson-Crick base pairs are formed by unique hydrogen-bonding interactions between the nitrogenous bases of DNA and RNA. The purine adenine associates specifically with the pyrimidine thymine in DNA (or the related unmethylated analog, macil, in RNA), and the pmine guanine interacts with the pyrimidine cytosine. These complementarity rules. 

Recall Which nucleotides break the rules of Watson-Crick base pairing when they are found at the wobble position of the anticodon Which ones do not ... 

Watson-Crick base pairing in complementary oligonucleotide strands keeps two rules of complementarity in both size and hydrogen-bonding patterns. Hydrophobicity and planarity in the bases also appear to be important for the stability of the double-helical structure. Designing new base pairs that vary in shape, size, and functionality has been usefiil in rmderstanding what is essential in the natural base pairing. 

The Watson-Crick rule of base pairing dictates that DNA double helices (e.g., B, A, and Z forms) be composed of two andparallel strands (aps-DNA). Accumulating evidence suggests that DNA conformations cannot always be fitted into standard molds, and diverse secondary structural forms of DNA can be constructed on the basis of variant H-bonding schemes collectively known as non-Watson-Crick base pairing. 

Perhaps the foundational principles for the comprehension of structural DNA technology can be listed as (i) sequence specific hybridization rules governed by Watson-Crick base pairing (Watson and Crick, 1953) (ii) connection of independent DNA species through sticky-ended cohesive interactions, for the formation of single molecule entities (Cohen et al., 1973 Qiu et al., 1997) and (iii) the realization of stable NAs junctions (Kallenbach et al., 1983 Winfree et al., 1998) and application of sequence symmetry minimization (Seeman, 1982 Seeman, 1990). 

Early work on DNA polymerase I led to the definition of two central requirements for DNA polymerization. First, all DNA polymerases require a template. The polymerization reaction is guided by a template DNA strand according to the base-pairing rules predicted by Watson and Crick where a guanine is present in the template, a cytosine deoxynucleotide is added to the new strand, and so on. This was a particularly important discovery, not only because it provided a chemical basis for accurate semiconservative DNA replication but also because it represented the first example of the use of a template to guide a biosynthetic reaction. 

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