Will mark in your own words, describe the base-pairing rules in any dna molecule.

The pairings between nucleic bases, forming "Watson-Crick" base pairs, are, on the one hand, adenine with thymine, and, on the other hand, guanine with cytosine. In addition, two nucleic acid sequences can match only antiparallel, that is to say between segments of opposite directions. Therefore, two nucleic acid sequences are complementary when the nucleic bases of one can pair with the nucleic bases of the other in the opposite direction to form two paired antiparallel segments.

The selective pairing of adenine (A) with thymine (T) and guanine (G) with cytosine (C) is based on the number of hydrogen bonds established between one of the purine bases and the one of the pyrimidine bases:

* Two hydrogen bonds between adenine (purine) and thymine (pyrimidines);

* Three hydrogen bonds between guanine (purine) and cytosine (pyrimidine).

Purity pairs, pyrimidine pairs, adenine-cytosine pair, or guanine-thymine pair are not normally formed. This selectivity is crucial for a large number of biochemical processes involving nucleic acids.

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.