Calvin cycle question

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JDHK

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10 turns of calvin cycle will produce which? The answer is 20 pgal.

The confusion I'm having with this is because different sources (my kaplan and online sources, etc) have different starting amount for one round of calvin cycle.

Some sources say you start with 3 rubiscos, which means you will have (3) 6 carbon molecules that split into (6) pga. Out of these we net 1 pgal which goes on to be used in other modifications to sugar. ---> in this case, we would net 10 pgal in 10 cycles, not 20.

Other sources say you start with 6 rubiscoes, which mean you will have (6) 6 carbon molecules that split into (12) pga. Out of these, 2 net pga, will be used in further modification. This seems to be the right answer at 20 net pgal for 10 cycles,

so I'm just supposed to discount the first source? is the first source entirely wrong?? I have a feeling i'm looking at it all wrong, because the question itself is part of the test in the same source (kaplan)

This mixup is driving me insane...

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To be Honest ....that is very detailed info for the DAT when it comes to the Calvin cycle. I would know for example. Where Calvin cycle occurs?? How many turns in the Calvin cycle to produce glucose. How many CO2. What is the starting material and products. Many will tell you that the real exam is not that detailed but very board. That's detailed. Good Luck
 
I think its that a 1 carbon CO2 reacts with a 5 carbon RuBP to ultimately make two 3 carbon G3P's (or PGAL). So for every turn you are creating (from 6 carbons) two 3 carbon PGAL's.

So here is the breakdown. 10 turns = 10 one carbon CO2's + 10 five carbon RuBP's = 10 six carbon molecules ---> each breaks down into two 3 carbon PGAL's = 20 PGAL's.

There's obviously ATP and NADPH and what not involved in this and the whole 6 turns = 1 glucose. But the question asked is much simpler, and I think just wants to know how many PGAL's are made per turn.

Hope that helps.
 
I basically just remember it as the following:

first 6 CO2 are accepted by 6 rubisco to make 12 phosphoglycerate

12 Phosphoglycerate along with 12 atp and 12 NADPH make 12 G3P

2 of these G3P will be used for Glucose and the remaining 10 G3P will combine with 6ATP to regenerate the 6 rubisco to repeat the cycle.
 
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I basically just remember it as the following:

first 6 CO2 are accepted by 6 rubisco to make 12 phosphoglycerate

12 Phosphoglycerate along with 12 atp and 12 NADPH make 12 G3P

2 of these G3P will be used for Glucose and the remaining 10 G3P will combine with 6ATP to regenerate the 6 rubisco to repeat the cycle.

This guy:thumbup:
 
I basically just remember it as the following:

first 6 CO2 are accepted by 6 rubisco to make 12 phosphoglycerate

12 Phosphoglycerate along with 12 atp and 12 NADPH make 12 G3P

2 of these G3P will be used for Glucose and the remaining 10 G3P will combine with 6ATP to regenerate the 6 rubisco to repeat the cycle.

This is what I thought too...which means one of the sources I was looking at is completely wrong... But see this too makes no sense with the sources that I'm looking at because the general consensus(this is another question) for "how many rounds of Calvin cycle does it take to make one glucose molecules (which are made by two g3p molecules)? If what you say is true, then it takes one cycle to make one glucose since one round gives a net of 2 g3ps. Some forums say it takes 3 rounds others say 6. It's all over the place. This isn't that specific of a problem :(. It's just I want the correct facts because they're relevant to the dat bio questions. Thanks and thanks in advance people
 
OHHHHH ohhhhhh oh my god. I finally got it clarified by my college text book. It's all correct, and it's so ambiguously represented but the thing is they all mean there is one rubp that goes in at a time, and a ratio of 3 rubp for 1 net g3p. So the trick is one at a time. They should really make that clearer. Thanks all =p
 
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