why do at and gc pair in dna ?

Description

https://en.wikipedia.org/wiki/GC-content

GC-content – Wikipedia
https://en.wikipedia.org/wiki/GC-content
GC content is found to be variable with different organisms, the process of which is envisaged to be contributed to by variation in selection, mutational bias, and biased recombination-associated DNA repair. The average GC-content in human genomes ranges from 35% to 60% across 100-Kb fragments, with a mean of 41%.

https://people.chem.ucsb.edu/kahn/kalju/chem110L/public/tutorial/PM3_Intro.html

Strength of Base Pairing Interaction in DNA
https://people.chem.ucsb.edu/kahn/kalju/chem110L/public/tutorial/PM3_Intro.html
The two base pairs in DNA are the AT base pair and the GC base pair. The AT base pair is held together by hydrogen bonds between the A base and the T base. Similarly, the GC base pair is held together by hydrogen bonds between the G base and the C base. How can we calculate interactions strengths? The strength of hydrogen bonding between nucleobases in the base pair is approximately equal to the enthalpy of the base-pairing reaction. You should remember from your introductory chemistry that …

https://www.sciencemag.org/news/2002/09/why-dna-spelled-atgc

Why DNA Is Spelled ATGC | Science | AAAS
https://www.sciencemag.org/news/2002/09/why-dna-spelled-atgc
Mac Dónaill noticed that the final digit acts as a parity bit: The four digits of A, T, G, and C all add up to an even number. Banishing all odd-parity nucleotides from the DNA alphabet reduces …

https://biology.stackexchange.com/questions/24261/why-does-a-pair-with-t-and-g-with-c

dna – Why does A pair with T and G with C? – Biology Stack …
https://biology.stackexchange.com/questions/24261/why-does-a-pair-with-t-and-g-with-c
If you would try to combine other bases than the canonical Watson-Crick pairs, the hydrogen bond donors and acceptors wouldn’t match. You need a donor/acceptor pair at each position. There are different base pairs possible, but these situations don’t really occur in DNA but in RNA. You can find G/U wobble base pairs and even base pairs that use different parts of the bases than the canonical base pairs, e.g. Hoogsteen base pairs.

https://pubmed.ncbi.nlm.nih.gov/6722876/

AT base pairs are less stable than GC base pairs in Z-DNA …
https://pubmed.ncbi.nlm.nih.gov/6722876/
When GC base pairs are present, the helical groove is systematically filled with two water molecules per base pair hydrogen bonded to the bases. Both of these water molecules are not seen in the electron density map in the segments of the helix containing AT base pairs, probably because of solvent disorder. This could be one of the features that makes AT base pairs form Z-DNA less readily than GC base pairs.

https://en.wikipedia.org/wiki/Base_pair

Base pair – Wikipedia
https://en.wikipedia.org/wiki/Base_pair
GC content and melting temperature must also be taken into account when designing primers for PCR reactions. Examples. The following DNA sequences illustrate pair double-stranded patterns. By convention, the top strand is written from the 5′ end to the 3′ end; thus, the bottom strand is written 3′ to 5′. A base-paired DNA sequence:

https://teaching.ncl.ac.uk/bms/wiki/index.php/DNA_Structure

DNA Structure – The School of Biomedical Sciences Wiki
https://teaching.ncl.ac.uk/bms/wiki/index.php/DNA_Structure
This explains why G-C rich DNA requires higher temperatures to denature it as there is greater bonding between base pairs. The pairing in DNA is highly specific- adenine only pairs with thymine and likewise, guanine only pairs with cytosine. This is because a purine can ony base pair with a pyrimidine (i.e. no purine-purine or pyrimidine-pyrimidine base pairs can occur). This is because the distance is too great for hydrogen bonds to form between two pyrimidines and there is not enough space …

https://findanyanswer.com/what-does-a-always-pair-with-in-dna

What does A always pair with in DNA? – FindAnyAnswer.com
https://findanyanswer.com/what-does-a-always-pair-with-in-dna
A base pair is one of the pairs A-T or C-G. Notice that each base pair consists of a purine and a pyrimidine. The nucleotides in a base pair are complementary which means their shape allows them to bond together with hydrogen bonds. The A-T pair forms two hydrogen bonds. In this manner, what are the correct base pairing rules for DNA?

https://cbm.msoe.edu/markMyweb/Hydrogen Bonding Tutorial_MARK.html

Hydrogen Bonding in DNA Base Pairs
https://cbm.msoe.edu/markMyweb/Hydrogen Bonding Tutorial_MARK.html
Guanine and cytosine make up a nitrogenous base pair because their available hydrogen bond donors and hydrogen bond acceptors pair with each other in space. Guanine and cytosine are said to be complementary to each other. This is shown in the image below, with hydrogen bonds illustrated by dotted lines. The button below the image highlights the hydrogen bonds between guanine and cytosine in a DNA double helix.

https://en.wikipedia.org/wiki/Nucleic_acid_thermodynamics

Nucleic acid thermodynamics – Wikipedia
https://en.wikipedia.org/wiki/Nucleic_acid_thermodynamics
The process of DNA denaturation can be used to analyze some aspects of DNA. Because cytosine / guanine base-pairing is generally stronger than adenine / thymine base-pairing, the amount of cytosine and guanine in a genome (called the GC content ) can be estimated by measuring the temperature at which the genomic DNA melts. [2]