Calvin Cycle?

[sfoksn]

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I have a source saying that 1 turn of Calvin Cycle produces:

2 PGAL
1 RBP
1 CO2

I don't really understand what they mean by this.

Can anyone clarify? Thank you.

 

[herkulease]

it just means exactly that. every turn of the cycle

2 PGAL
1 RBP
1 CO2

is produced. It requires 6 turns make enough products to make glucose.

 

[sfoksn]

But.. I thought 1 PGAL is 3 carbon molecule?

I thought 2 PGAL joins to become 1 glucose molecule, no?

 

[Avery07]

But.. I thought 1 PGAL is 3 carbon molecule?

I thought 2 PGAL joins to become 1 glucose molecule, no?

This is correct but you still have another 10 PGAL that is used to regenerate 6 RuBP.

Think of this. 1 turn brings in 1 CO2 molecule. That's one carbon. Glucose needs 6. 6 turns = 6 carbons = glucose.

The Calvin Cycle is very confusing when you get to the intricate details. I still don't fully understand the biochemistry of it but have the understanding that there are all these intermediate compounds which exist in the cycle to function to help make glucose through different intermediate reactions. It takes 6 turns to get 6C into the cycle and through that an extra 2PGAL are created which can then go off to make a glucose molecule.

 

[sfoksn]

Thank you everyone, always so helpful.

 

[Frederico Albin]

lol i was confused what you guys meant by PGAL lol... i am more used to seeing G3P 🙂

 

[Avery07]

lol i was confused what you guys meant by PGAL lol... i am more used to seeing G3P 🙂

It took me a while to get that difference down lol. I have both memorized just in case.

 

[Erhatstil]

i'm failing to see where CO2 is produced in the calvin cycle. was that a misprint or am i missing something??

 

[Frederico Albin]

i'm failing to see where CO2 is produced in the calvin cycle. was that a misprint or am i missing something??

CO2 is not produced in the calvin cycle, RuBP binds to CO2 and through many reactions it is turned into sugars, amino acids, and fatty acids. More known as carbon fixation. CO2 is one of the reactants, not a product.

6CO2 + 12H2O + sunlight -> C6H12O6 + 6H2O + 6O2

Hope that helps.

 

[Erhatstil]

yeah i just couldn't figure out why the first posters seemed to concur on CO2 being one of the products when its def not

 

[Erhatstil]

CO2 is not produced in the calvin cycle, RuBP binds to CO2 and through many reactions it is turned into sugars, amino acids, and fatty acids. More known as carbon fixation. CO2 is one of the reactants, not a product.

6CO2 + 12H2O + sunlight -> C6H12O6 + 6H2O + 6O2

Hope that helps.

i don't think u want that 6H20 on the product side, just sayin

 

[Frederico Albin]

i don't think u want that 6H20 on the product side, just sayin

hehehe, yeah, I should have used the simpler version 🙂