The Calvin cycle

2nd set of reactions in photosynthesis
Named after Melvin Calvin
also called dark reaction
can occur in light OR dark
requires:
	enzymes
	products of light reaction
		ATP
		NADPH+
used by C3 plants
occurs in stroma("cytoplasm of the chloroplast")


Step 1
Step 2
Step 3
Carbon fixation by the Calvin cycle
	CO2 is bonded(fixed) into organic compounds
		carbon fixation

The balance sheet for Photosynthesis

each turn of the cycle fixes one CO2 molecule

PGAL is a 3-carbon molecule => takes 3 turns of the cycle to produce each PGAL

each turn uses:
	2 ATP
	2 NADPH+
	1 ATP

3 turns use:
	9 ATP
	6 NADPH+

When cycle has turned 6 times, there is 6(CH20) = C6H12O6  (glucose)

Some PGAL and other molecules are built into:
	(heterotrophs depend on autotrophs for these)
	amino acids
	lipids
	carbohydrates
		monosaccharides
			glucose
			fructose
		disaccharides
			sucrose
		polysaccharides
			glycogen
			starch
			cellulose

Glucose and formulas

general formula for carbohydrates

	CO2 + H2O + light => (CH2O) + O2

the formula is often replaced by using a specific carbohydrate (i.e. glucose)

	6CO2 + 6H2O + light => C6H12O6 + 6O2

Glucose is not actually produced by the
pathways of photosynthesis. It is included
in the equation mainly to emphasize the
relationship between photosynthesis
and respiration!!!
Rate of photosynthesis
	affected by environment
		
			plateau-maximum rate of photosynthesis
		

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