After all, numerous kinds reactions are known and PCR is just one of them.
For example, we say: “the Arbuzov reaction”, “the reaction between baking soda and vinegar” etc. Moreover, scholarly articles frequently use “the polymerase chain reaction”:


However, there are many instances when “polymerase chain reaction” is used without article: https://en.wikipedia.org/wiki/Polymerase_chain_reaction


Is the latter usage idiomatic? Can "PCR" be treated as a name for some reason? Is there any difference between the two usages?

  • That first link refers to a specific PCR. There are not many that use it without. And several have the the plural noun and the Wikipedia thing is wrong. – Lambie Sep 13 '19 at 17:47
  • Then it’s not only Wikipedia, but also some respectable peer-reviewed journals: sciencedirect.com/topics/neuroscience/polymerase-chain-reaction – Zak Sep 14 '19 at 6:46
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    First, I am not a scientist but now I see why there is no article. Polymer chain reaction is an uncountable noun as used here. That's why. It is a method. So, the use allows one not to use the article. It's just like: nuclear fission or nuclear fusion. A non-count noun. – Lambie Sep 17 '19 at 23:28
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    I have updated my answer, and there is a reason: it is viewed as a non-count noun, like nuclear fusion or fission. It is a method. – Lambie Sep 17 '19 at 23:32

The Wikipedia article is right for this term: polymerase chain reaction.

  • An atomic reaction is a complex process. [general, indefinite]
  • Atomic reactions were studied by students during [whatever].

  • The atomic reaction of [whatever] was difficult to measure. [specific]

  • A polymerase chain reaction is a [whatever]; [singular, general, indefinite]

  • EDIT: Polymerase chain reaction is [whatever]; singular, general, indefinite, non-countable. But it could take an A.

To describe a thing that is countable, use a or the plural of the noun.

  • The polymerase chain reaction or reactions that occurred when [etc]; not general, specific.

In short,

  • The indefinite article "a" is used for unspecified generalities.
  • The plural of a countable noun is used for specified generalities.

In the first link from the OP: Overlap extension represents a new approach to genetic engineering. Complementary oligodeoxyribo-nucleotide (oligo) primers and the polymerase chain reaction are used to generate two DNA fragments having overlapping ends.

"the polymerase chain reaction" because for the author there is only one there: it is specific.

EDIT: It turns out that polymerase chain reaction is used by biologists as a non-count noun just like: nuclear fission or nuclear fusion.

I had no way of knowing until I read all about it. Now it makes sense. It would never be countable in biology and therefore would never take an s.

  • -1; see my reply in the comments on my own answer for justification. – TypeIA Sep 13 '19 at 17:26
  • (That said, this answer does correctly describe the rules for countable and uncountable nouns in general: but I disagree that PCR must be countable.) – TypeIA Sep 13 '19 at 17:31
  • There are all kinds of issues with that google scholar search results. I shall not pick apart each one. The first one is fine because it has "the" and is specific. And here, is the plural noun for a generality: sciencedirect.com/science/article/abs/pii/037811199090145H That said, Wikipedia is not always reliable. – Lambie Sep 13 '19 at 17:43

As you probably know, there is no authoritative organization that decides what is or isn't correct in English. This is in contrast to other languages like French (l'Académie française) or German (der Duden). So in English, whether something is "idiomatic" or not is determined by its usage and acceptance.

Because you've found several examples of both usages in respectable literature, I think the only answer is that it is acceptable either way (with or without an article). I don't think there is any difference in meaning.

  • This is not correct regardless of the fact there is no authority. They are many authoritative grammar books and here, they would all agree. No indefinite article is a mistake for the OP's question. – Lambie Sep 13 '19 at 17:10
  • @Lambie I think you're contradicting yourself. There are indeed many grammar books, but none of them are authoritative. Given that OP found this usage by a highly respected, peer-reviewed scientific journal, in addition to other sources, I stand by my answer. For a grammatical justification by analogy, compare "overreaction" which is fine with no article: "Overreaction is bad." If scientists use it this way, that's fine by me. – TypeIA Sep 13 '19 at 17:25
  • No,I'm not. Just because some noun can also have an uncountable meaning, that does not change what I said. "overreaction" is psychology, not biology. Not all the OP's examples are respectable literature and every one that is follows the rules I laid out. – Lambie Sep 13 '19 at 17:46

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