Basically
CO2 from air gets fixed to a 5 carbon molecule to become a 6 Carbon molecule.
The 6 Carbon molecule becomes unstable and splits into two 3C + 3C molecules.
A sugar molecule is produced and broken off. The 3C + 2C combine to make a
5 carbon compound again to fix another Carbon dioxide molecule. . . . Easy !!!
July 9.'02 I have spent a lot of time on the calvin Cycle and how the process
works. It has been confusing to I have spent too much time on it really. I
think science isn't sure exactly.
RuBP a 5 carbon compound that always starts the cycle:
CH2O -ph
CO + < < a Carbon Dioxide from the atmosphere is fixed here
CH2O
CH2O
CH2O -ph
What happens here is this RuBP gets the carbon dioxide and splits in half.
COOH . . . . . . . COOH
CH2O . . . . . . . . CH2O
CH2O -ph . . . . . CH2O -ph
I think that 3 molecules at a time are fixed. When the cycle goes around
twice then 1 molecule of glucose is made. That means 3 RuBP circle together.
I'm not sure because the books aren't clear. Today I'm guessing 3 at a time.
CCCCCph . . . . CCCph
CCCCCph . . . . CCCph . . . CCC
CCCCCph . . . . CCCph . . . CCC
. 3 C5 . . <<< . . . 3 C3 . + . 2 C3 . . . >> 1/2 sugar
Read from right to left, starting with sugar out :
This shows Carbons and sugar just made and leaving cycle and the cycle just after.
This idea with the dashes is to show the cabons as - - - and where
the other molecules come in.
- - - - - 3 RuBP
- - - - -
- - - - -
3 CO2 are fixed then splits
- - - - - - 6 PGA
- - - - - -
- - - - - -
NADPH + ATP
3 carbon sugar out
- - - - - - 5 PGAL
- - - - - -
- - -
Rearranges here somehow
- - - - -
- - - - -
- - - - -
ATP here to make RuBP again. EasY !!!
Cycle showing Carbons coming in at top and ½-sugar going out at bottom :C C C - - - - - - - - - - C
- - - - - - - - - - C
- - - - - - - - - - C
rearrangement splitting in half
- - - - - - - - - - - C
- - - - - - - - - - - C
- - - - - - - - C - - C out A 3 Carbon sugar out that makes all the differance in the world.
July 22, 02
I used the pre tag for this ---dashes diagram. I am trying to show something
without all the clutter that lots of chemistry pages give to teach something.
I think I have explainded this subject pretty good. It was't EAsy.
Part of my idea is to have a place to come back and review. People will
know where these various subjects are kept to refresh our memory.
Rubisco molecule Remember this molecule takes carbon from the air.
added Jan.15, '02
Not to go in another direction of study. Of interest this molecule
that makes DNA is made at point if sugar don't split.About Glucose . . . . added Jan. '05
Here is this Animation to help see Carbon fixation . . . . wait to load.
Click Play button.
. . . Amazing process of Carbon entering cycle
Return to Main Page of Nitrogencycle.org
May '07 - I haven't seen this page in 3 years, I think. Terry C.
Made a few slight changes.
. . . Amazing process of Carbon entering cycle
