+0
Hi. In the Collins COBUILD Advanced Learner's English Dictionary, it has this definition for the word "enzyme," and I wonder if a comma before the word (pronoun?) "which" would be correct. Please help. I also think that the word in capital letters "TECHNICAL" (in brackets) means the word is technical in terms of its use.

An enzyme is a chemical substance that is found in living creatures which produces changes in other substances without being changed itself. [TECHNICAL]
Comments  
I wonder if a comma before the word (pronoun?) "which" would be correct.-- No; the following clause is a critical part of the definition of 'enzyme'.

I also think that the word in capital letters "TECHNICAL" (in brackets) means the word is technical in terms of its use. -- That's right...except that it's really not terribly technical. Many laymen know what enzymes are.
Hi. Thank you. I think comma would be correct (or possibly optional in this case) before the word "which" in the definition I found in the Collins COBUILD Advanced Learner's English Dictionary. I feel/think the part "that is found in living creatures," which seems to identify the sort of chemical substance an enzyme is -- in this case, that that is found in living creatures --might cause misunderstanding on the part of the reader. The reader might mistakenly think the pronoun "which" refers to the living creatures and not to the chemical substance (as I think it should refer to)

An enzyme is a chemical substance that is found in living creatures which produces changes in other substances without being changed itself. [TECHNICAL]
Teachers: We supply a list of EFL job vacancies
No, they won't. The verb is 'produces', so 'creatures' cannot be its subject.
Hi. Thank you again.

Do you think the placement of commas for these is correct? I think what I am trying to ask is if some words or phrases or clauses (possible?) exist and if those can leave a possibility of readers of the sentence with them not getting clear meaning of the sentence, would putting a comma before what seems to be a dependent clause (or what seems to be a clause (another clause?) with a relative pronoun "which") that starts with the pronoun "which" be correct? (Not sure I asked correctly what I wanted to ask, though)

Would you place commas here?

1. XXX are toys that can be used by dogs (a comma or no comma?) which can be healthy, too.

2. XXX are toys that can be used by dogs (a comma or no comma?) which they can help them get some good exercise.
Anon, I think you might be missing the point. An enzyme is not a chemical substance that is found in living creatures because there are many chemical substances found in living creatures that are not enzymes. However, by adding a comma you would define it that way --- and, by the way, they also happen to produces changes in other substances without being changed itself. That is not right. The entire clause belongs to the definition, so a comma before which is wrong.

They only used which instead of that for style reasons.
Students: We have free audio pronunciation exercises.
1. XXX are toys that can be used by dogs, (comma) which can be healthy, too.
2. XXX are toys that can be used by dogs, (comma) which can help them get exercise.

Ambiguities are resolved by revising one's writing:

2. XXX are toys that can be used by dogs ( no comma) to help them get exercise.
Hi. Thank you.

If the phrase "living creatures" were happen to be (for the illustration purpose of asking this question) "a living creature" in the singular, would you say placing a comma before the pronoun "which," although the part that follows (including it), which is "which produces changes in other substances without being changed itself" is correct eventhough the part is retrictive (essential) to the whole sentence? (I am not sure I asked the question correctly to reflect what I wanted to say, though)

Definition of the word "enzyme" in the Collins COBUILD Advanced Learner's English Dictionary:

An enzyme is a chemical substance that is found in living creatures which produces changes in other substances without being changed itself. [TECHNICAL]
Then you would have to recast the sentence, since both the restrictive and non-restrictive forms would ambiguously refer to 'creature':

An enzyme is a chemical substance that is found in a living creature and which produces changes in other substances without being changed itself.
Site Hint: Check out our list of pronunciation videos.