light independent reactions

calvin cycle steps

1. fixation of atmospheric carbon diocide by ribulose 1,5-bisphosphate to form two molecules of 3-phosphoglycerate

2. reduction of 3-phosphoglycerate to form glyceraldehyde 3 phosphate which can be converted to hexoses

3. regeneration of ribulose 1,5-bisphosphate from 2G3P so that more CO2 can be fixed

negatives of rubisco

• poorly selective - sometimes bind to oxygen to create waste product

• very slow

function of rubisco in calvin cycle

• catalyses combination of ribulose 1,5-bisphosphate with CO2

  • forms two molecules of 3-phosphoglycerate

where is rubisco found

• stromal surface of thylakoid membrane

most abundant protein in plants

rubisco

reduction steps

• 3-phosphoglycerate is an intermediate in glycolysis and gluconeogenesis

• phosphorylated to 1,3-bisphosphoglycerate with consumption of ATP

• then reduced to glyceraldehyde 3-phosphate with oxidation of NADPH

what reduces 1,3-bisophosphoglcyerate to glyceraldehyde-3-phosphate?

• oxidation of NADPH

regeneration steps

• 3 molecules of ribulose-1,5-bisphosphate needed to be regenerated for calvin cycle to continue

• 5 of the 6 glyceraldehyde-3-phosphate molecules are used to regenerate 3 molecules of ribulose-1,5-bisphosphate

how many times for cycle to go around to produce glucose

• production of glucose requires cycle to occur 6 times

what do plants convert glucose/fructose into and where

• sucrose in cytosol

• starch in chloroplast

• cellulose in cell wall

how many molecules of atp and nadph are consumed for each co2

• 3 molecules of ATP

• 2 NADPH

photorespiration

• when co2 levels are low

• oxygen added to ribulose-1,5-bisphosphate

where does most of the glyceraldehyde 3-phosphate get transported to

• out of the chloroplast

• through antiport system