Question

Why purine always pairs with pyridine? Why not purine-purine or Pyridine-Pyridine pairs take place?
Please no need to give googled answer.​

Answer 1

I know that adenine bonds with thymine and guanine bonds with cytosine (known as the base pair rule). It also has to do with DNA.

Also...

-Purines are adenine and guanine nitrogen bases.

-Pyrimidines are thymine and cytosine nitrogen bases.

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Answer 2

Explanation:

purine always pairs with pyridine

Because hydrogen bonds are not as strong as covalent bonds, base pairings can easily be separated, allowing for replication and transcription. Because purines always bind with pyrimidines – known as complementary pairing – the ratio of the two will always be constant within a DNA molecule.