dog25
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Hey so i was wondering why do enzymes lower the activation energy needed for a reaction ,pls can u explain in depth because i have searched it up read textbooks and i just can not grasp the idea
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golgiapparatus31
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The substrate will bind to the active site, forming an enzyme-substrate complex. The enzyme will facilitate breakage/formation of bonds, transfer of electrons/protons, etc.. so activation energy is lowered and reaction goes faster
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Onioniem
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(Original post by dog25)
Hey so i was wondering why do enzymes lower the activation energy needed for a reaction ,pls can u explain in depth because i have searched it up read textbooks and i just can not grasp the idea
One example (anabolic reaction): the enzyme binds two molecules to form an ESC and forces them together in the right orientation. The activation energy is lowered because the molecules are no longer free to move randomly, so they have lower entropy. This means deltaS of the reaction is lowered which by extension means the activation energy is lower This is because high entropy is always favoured, so going from high entropy to low entropy (i.e. without enzyme) requires high energy – whereas going from low entropy -> low entropy requires less energy.

I may have used some of the terms incorrectly, so someone else feel free to correct me, but I think this is one explanation (out of many, since enzymes work differently)
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dog25
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sorry all the language here is pretty complex i dont really get it and the main question i have is why exactly does breaking up the substrate molecule lower the activation energy. what is it about smaller molecules that allows chemical reactions to happen faster?
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golgiapparatus31
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(Original post by Onioniem)
One example (anabolic reaction): the enzyme binds two molecules to form an ESC and forces them together in the right orientation. The activation energy is lowered because the molecules are no longer free to move randomly, so they have lower entropy. This means deltaS of the reaction is lowered which by extension means the activation energy is lower This is because high entropy is always favoured, so going from high entropy to low entropy (i.e. without enzyme) requires high energy – whereas going from low entropy -> low entropy requires less energy.

I may have used some of the terms incorrectly, so someone else feel free to correct me, but I think this is one explanation (out of many, since enzymes work differently)
Does activation energy depend on entropy??
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dog25
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i am in y9 so i dont even know what that means
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golgiapparatus31
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(Original post by dog25)
sorry all the language here is pretty complex i dont really get it and the main question i have is why exactly does breaking up the substrate molecule lower the activation energy. what is it about smaller molecules that allows chemical reactions to happen faster?
Do you know the term enzyme-substrate complex? It's not the process of breaking up the substrate molecule that lowers the activation energy. It is the enzyme which lowers the activation energy.

The substrate will bind to the active site. The enzyme will put strain on the bonds of the substrate, making it easier to break. That's why the activation energy is lowered
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dog25
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ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhh wait so the enzyme does not literally break up the substrate molecule
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golgiapparatus31
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(Original post by dog25)
ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhh wait so the enzyme does not literally break up the substrate molecule
It does. By putting strain on the bonds, the bonds are broken
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Khalid Al-Raisi
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(Original post by dog25)
ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhhhhhhhhhh wait so the enzyme does not literally break up the substrate molecule
Nope. When the substrate binds to the active site the structure of the substrate changes which lowers the activation energy, the activation energy decreases because the electrons are moved and some bonds may be broken.
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golgiapparatus31
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(Original post by Khalid Al-Raisi)
Nope. When the substrate binds to the active site the structure of the substrate changes which lowers the activation energy, the activation energy decreases because the electrons are moved and some bonds may be broken.
I have to disagree. https://www.bbc.co.uk/bitesize/guide...and%20glycerol

The enzyme does break the molecules e.g in a hydrolysis
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Khalid Al-Raisi
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(Original post by golgiapparatus31)
I have to disagree. https://www.bbc.co.uk/bitesize/guide...and%20glycerol

The enzyme does break the molecules e.g in a hydrolysis
The enzyme does not break the substrate on its own, it changes the structure of the substrate to lower the activation energy, the substrate won't be changed into a product by the enzyme itself it requires some extra energy.

https://www.gceguide.xyz/files/e-boo...Coursebook.pdf
page 56
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golgiapparatus31
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(Original post by Khalid Al-Raisi)
The enzyme does not break the substrate on its own, it changes the structure of the substrate to lower the activation energy, the substrate won't be changed into a product by the enzyme itself it requires some extra energy.

https://www.gceguide.xyz/files/e-boo...Coursebook.pdf
page 56
Thanks for the text
I quote a paragraph from page 56:
Lysozyme is a natural defence against bacteria that is
found in tears, saliva and other secretions. It breaks
the polysaccharide chains that form the cell walls of
bacteria.


The book says [lysozyme] breaks the polysaccharide ... It is true that the substrate must have energy greater or equal to the reduced activation energy though
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Khalid Al-Raisi
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(Original post by golgiapparatus31)
Thanks for the text
I quote a paragraph from page 56:
Lysozyme is a natural defence against bacteria that is
found in tears, saliva and other secretions. It breaks
the polysaccharide chains that form the cell walls of
bacteria.


The book says [lysozyme] breaks the polysaccharide ... It is true that the substrate must have energy greater or equal to the reduced activation energy though
Then it's just that we didn't understand each other well. I said that enzymes do not break up the substrate on its own because energy equal to or greater than the activation energy is also required.
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golgiapparatus31
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(Original post by Khalid Al-Raisi)
Then it's just that we didn't understand each other well. I said that enzymes do not break up the substrate on its own because energy equal to or greater than the activation energy is also required.
Great!
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RoyalSheepy
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(Original post by dog25)
Hey so i was wondering why do enzymes lower the activation energy needed for a reaction ,pls can u explain in depth because i have searched it up read textbooks and i just can not grasp the idea
(Original post by dog25)
i am in y9 so i dont even know what that means
Simply put: enzymes act as a biological catalyst providing an alternative pathway for a reaction.
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