I have read that enzymes act as catalysts to reactions in our bodies and that they are extremely target-specific.
My question is how did our body know that a particular enzyme could act as a catalyst for a particular reaction? How did de we get the perfect combination of reactants and their catalysts?
Note:- I am not a person who is studying biology so I might not know that which is pretty obvious to you people.
Anyways, the least expected answer is that ancient aliens carried out some sort of Worldwide Enzyme Injection Programme ;-)

Edit:- By the knowledge gained after asking this question I've figured out that it might be something like this -
There were species which had a different set of enzymes than us but as these weren't the right match the species perished. Those who had the right enzymes survived. Am I right ?

  • $\begingroup$ The problem here is that you've reversed cause and effect. The body doesn't "decide" to create a new enzyme for some purpose. Instead, various slightly (or sometimes, but not very often, drastically) modified enzymes happen to be produced by genetic rearrangements. If those new enzymes happen to do something useful, they're probably conserved in following generations. Remember that "our body" is the product of a billion or so years of evolution, and that variations on those enzymes are shared by all life. $\endgroup$ – jamesqf Feb 13 '17 at 19:34
  • $\begingroup$ @jamesqf Do you mean all the catalysts were tried one by one ,by nature, and then the right ones were fixed by evolution ? I had thought of this answer before asking, but the sheer time it would take made me ignore this one. Anyways, I think with references and all you should make this into an answer. $\endgroup$ – Raghav Feb 13 '17 at 23:18
  • $\begingroup$ Raghav: Not one by one, but in a very massively parallel process, with each living creature potentially getting to try out slightly different versions, and only the survivors getting to reproduce. $\endgroup$ – jamesqf Feb 14 '17 at 4:48
  • $\begingroup$ Please check this site out. You seem to have some misconceptions about evolution. $\endgroup$ – WYSIWYG Feb 14 '17 at 5:52

I can understand why your asked this sort of question so I will clear your doubts one by one.

First of all Enzymes are not scattered inside our body, every enzyme is localised in a particular orgenelle or compartment of protoplasm in the cell, where they play their specific role.

Such as the enzymes of glycolysis ( the process by which you create ATP and breakdown glucose to pyruvate) are present in cytoplasm where as the enzymes for TCA ( Oxidative-decarboxylation of AcetylCoA) are present in mitochondria.

Enzymes are very specific.(1) If you have heard of lock and key hypothesis which states that an enzyme binds to the substrate that is complementary to its active site. Enzymes have very high specificity for their substrates the active site where reactions happen are somewhat complementary to the Enzyme substrate complex and thereby it provides the binding energy that lower downs the activation energy of that particular reactions that enzyme is going to catalyse.

I hope that helps!

References: (1) please refer to lehninger principles of biochemistry for further information!

  • $\begingroup$ Hi welcome to Biology.StackExchange! Please provide citations to support your claims. We expect and encourage citations or other references to ensure accuracy of responses. "Answers" without citations/references are better off as comments. Thanks! $\endgroup$ – theforestecologist Feb 13 '17 at 17:28
  • $\begingroup$ Hi I am somewhat new to this forum so I just posted an answer without giving any references but thanks will keep in mind for next time! $\endgroup$ – Harsimran kaur Feb 13 '17 at 17:36

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