Carbon Fixation and carbohydrate synthesis
- Carbon fixation reaction: converted into another carbon compound: MOST IMPORTANT
- plants/algae = occurs in stroma
- Product = three carbon compound: glycerate 3-phosphate
- carbon dioxide reacts with a five-carbon compound: ribulose biphosphate (RuBP) = to produce 2 molecules of glycerate 3-phosphate
- stroma contains large amounts of rubisco (enzyme which catalyses reaction) to maximize carbon fixation
Regeneration of RuBP
- triose phophate: first carbohydrate produced by the light-independent reactions
- hexose phosphate produced with two triose phosphate
- starch produced with hexose phosphate combined by condensation reaction
- Calvin cycle: a cycle formed by the reaction of RuBP being consumed and produced in the light-independent reaction s of photosynthesis
Identifying the First Products of Carbon Fixation (p.112)
1) Glycerate 3-phosphate is the first product of carbon dioxide fixation because looking at the graph, the glycerate 3-phosphate showed a high amount in the first few seconds yet later, the amount has decreased through time. Also, all the other phosphates and molecules use the glycerate 3-phosphate in order to synthesize increasing gradually the percentage of radioactivity. Since carbon fixation reaction is being experimented, the product of glycerate 3-phosphate.
2) The conversion of glycerate-3-phosphate to triose phosphate is evident since the concentration of triose phosphate increases as the concentration of the glycerate-3-phophate decreases with time, according to the graph. This shows how the glycerate-3-phophate is being used to produce more of the triose phosphate. Thus, the glycerate-3-phosphate is an essential material in order for the conversion to the triose phosphate. The conversion of glycerate-3-phosphate to sugar phosphates are also evident as its production rises as the glycerate-3-phosphate falls as well. Hydrogen is added to the glycerate-3-phosphate in order to perform a reduction reaction to produce the sugar and triose phosphate.