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Cellular Respiration
What happens before cellular respiration?













Home | Key Terms/ Key Words | What happens before cellular respiration? | Glycolysis | Transition Reactions | Kreb's Cycle | The electron transport chain | Fermentation




















Before cellular respiration can take place, glucose must be created. Glucose is created in the Calvin cycle. The Calvin cycle is a series of reactions that take place in the stroma of a thylakoid cell and uses ATP and NADPH. The Calvin cycle is divided into three phases; Carbon Fixation, Reduction, and Regeneration of RuBP (ribulose-1,5-diphosphate).
In the first phase, carbon gas is taken from the atmosphere and attaches to RuBP. It creates a six carbon molecule. Almost immediatly this molecule divides into two 3-carbon molecules called PGA (phosphogylcerate). The enzyme RuBP carboxylase catalyzes this reaction. It is called C3 fixation; two 3-carbon molecules are produced.
In the second phase, the stroma of the cell allows reactions to reduce PGA into PGAL. First ATP gives off it's phosphates and PGA gets transformed into PGAP (biphosphogylcerate). Secondly, a molecule of NADPH gives up a hydrogen ion and some of it's electrons to PGAP, this reduces PGAP into PGAL (phosphogyleraldehyde).
At this point there are six molecules containing three carbon and one phosphate.
In the last phase, one of the molecules (containing three carbon and one phosphate) is taken away. At this point you are left with five molecules, and it is called G3P. Then three ADP are added and you end up with your begining molecule of RuBP.
Once this whole cycle is done twice, Glucose is created.
 
 

Thylakoid

thylakoid1.jpg
















 
RuBP
P-CCCCC-P
P-CCCCC-P
P-CCCCC-P
 
PGA (ATP is added)
P-CCC  P-CCC
P-CCC P-CCC
P-CCC P-CCC
 
 PGAP  (NADPH is added)
P-CCC-P P-CCC-P
P-CCC-P P-CCC-P
P-CCC-P P-CCC-P
 
PGAL
CCC-P CCC-P
CCC-P CCC-P
CCC-P CCC-P
 
G3P
CCC-P CCC-P
CCC-P CCC-P
CCC-P            
 
RuBP   (ADP is added)
P-CCCCC-P
P-CCCCC-P
P-CCCCC-P

glucose1.jpg

Glucose