Super Funky Bio Question! Must read!

[wired202808]

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Which option below is true regarding enzymes?

A. All enzymes are proteins.
B. A non-spontaneous reaction can become spontaneous in the presence of an enzyme.
C. Enzymes usually exhibit irreversible binding.
D. A single enzyme can catalyze a reaction in both the forward and reverse direction.
E. The activation energy of a reaction generally increases in the presence of an enzyme.


So the answer was D; which I didnt know could be true, but after googling it I realized its true. HOWEVER, I picked A and the explanation says Some molecules exhibit the catalytic properties of enzymes and are not proteins (therefore it cannot be A.) meanwhile Wikipedia defines enzymes as Enzymes (pronounced /ˈɛnzaɪmz/) are proteins that catalyze (i.e., increase the rates of) chemical reactions.

Has anyone seen an enzymes thats not a protein? While I get that D is a viable answer (now that I know it and memorized it) I still believe A is a correct choice as well (this was my answer.)

Thoughts?

 

[Clancyp]

Which option below is true regarding enzymes?

A. All enzymes are proteins.
B. A non-spontaneous reaction can become spontaneous in the presence of an enzyme.
C. Enzymes usually exhibit irreversible binding.
D. A single enzyme can catalyze a reaction in both the forward and reverse direction.
E. The activation energy of a reaction generally increases in the presence of an enzyme.


So the answer was D; which I didnt know could be true, but after googling it I realized its true. HOWEVER, I picked A and the explanation says Some molecules exhibit the catalytic properties of enzymes and are not proteins (therefore it cannot be A.) meanwhile Wikipedia defines enzymes as Enzymes (pronounced /ˈɛnzaɪmz/) are proteins that catalyze (i.e., increase the rates of) chemical reactions.

Has anyone seen an enzymes thats not a protein? While I get that D is a viable answer (now that I know it and memorized it) I still believe A is a correct choice as well (this was my answer.)

Thoughts?

I would have said the same last year. But recently, they have discovered some RNA that can act as 'biological catalyst' thus an enzyme. But I feel like even D is a little.... broad to be an answer too.

 

[buckey]

ribozymes, which are molecules of RNA, are rare but they do function as enzymes. I've seen questions that define enzymes as only proteins and them that use this exception, the best way to go about it is by process of elimination.

 

[FROGGBUSTER]

ribozymes, which are molecules of RNA, are rare but they do function as enzymes. I've seen questions that define enzymes as only proteins and them that use this exception, the best way to go about it is by process of elimination.

👍 A is false.

 

[wired202808]

ribozymes, which are molecules of RNA, are rare but they do function as enzymes. I've seen questions that define enzymes as only proteins and them that use this exception, the best way to go about it is by process of elimination.

thanks buck thats a tough one, i guess i just gotta memorize that one now! tricky but better to get it wrong now than on the real thing.

 

[yappy]

B. A non-spontaneous reaction can become spontaneous in the presence of an enzyme.

Is this untrue because in a state function the path does not mater, and delta H doesnt change in presense of a catylist; only the path?

 

[nondescriptive]

A is false. In ochem, when you do acid catalyzed reaction, the acid is a catalyst but not necessarily a protein.

 

[buckey]

B. A non-spontaneous reaction can become spontaneous in the presence of an enzyme.

Is this untrue because in a state function the path does not mater, and delta H doesnt change in presense of a catylist; only the path?

This is untrue because a non-spontaneous reaction implies that the delta g is positive. Since the delta g is positive then energy is required to run the reaction. A catalyst does not impart energy into the system is just lowers the energy of activation that would lead to an overall decrease in energy

 

[AlbinoPolarBear]

Lol, this is so funny because I saw this journal article a while back that was super interesting.

Not only are proteins and RNA capable of enzymatic activity, but so is DNA.

http://en.wikipedia.org/wiki/Deoxyribozyme

Of course, these aren't found in nature, like protein and RNA enzymes, but you would have to artificially select them through an intensive process. Still pretty cool.

 

[AlbinoPolarBear]

A is false. In ochem, when you do acid catalyzed reaction, the acid is a catalyst but not necessarily a protein.

Right answer, wrong reasoning.

A. All enzymes are proteins.

Enzymes are catalysts, but not all catalysts are enzymes.

 

[nondescriptive]

Actually, I asked my professor and he said 99% of enzymes are protein. A is not true. I think its also a question that is debatable.

 

[wired202808]

Actually, I asked my professor and he said 99% of enzymes are protein. A is not true. I think its also a question that is debatable.

ye its confusing because KBB had enzymes as proteins and so did wikipedia, but it wasnt a fully inclusive definition.

 

[wired202808]

Right answer, wrong reasoning.

A. All enzymes are proteins.

Enzymes are catalysts, but not all catalysts are enzymes.

i actually found the same question in chads bio chem quiz! lol good stuff!

 

[tvndental]

My answer was D when I read the question.

First of all, when you are doing a true/false question. The answer is usually not one that says "ALL" because there will always be exceptions to everything especially in science.

Also you have to remember that an enzyme is not just protein. It can be composed up with a lot of things, RNA, DNA, ions, etc. So the definition of enzyme is not enzyme=protein.

"A non-spontaneous reaction can become spontaneous in the presence of an enzyme."
A enzyme does not change the direction of the reaction. It just speeds it up things up to equilibrium in the direction it was going to in the first place.

"A single enzyme can catalyze a reaction in both the forward and reverse direction."
If you can visualize an energy diagram and what an enzyme does you find that all it does is reduce the activation energy (the hill is lower). This benefits both the forward and backward reaction. It doesn't play favorites. The direction depends on your initial state.