D-glyceraldehyde 3-phosphate triose ..

Second, DHA-phosphate is converted into glyceraldehyde-3-phosphate by the enzyme .
Photo provided by Flickr

Photosynthesis triose phosphate | …

Overall, to form six molecules of glyceraldehyde 3-phosphate () in equilibrium with dihydroxyacetone phosphate. In the third stage, five of the six molecules of triose phosphate() are used to (), the starting material. , can be used to make hexoses for fuel and building materials, sucrose for transport to non-photosynthetic tissues, or starch for storage (Fig. 8.11). Thus .

So, at this point, 1 glucose has been converted into 2 glyceraldehyde-3-phosphates.
Photo provided by Flickr

photosynthesis Flashcards | Quizlet

Thus, in summary, for every molecule of triose phosphate produced by photosynthetic CO2 assimilation, are required. NADPH and ATP (2:3) as they are consumed in the Calvin cycle.

Next, glyceraldehyde-3-phosphate is converted into 1,3-bisphosphoglycerate by the enzyme .
Photo provided by Flickr

It is important to understand the roles of ribulose bisphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate to triose phosphate, NADPH + H+, ATP, and the regeneration of RuBP. The red-circled numbers in the Figure 1 correspond to the numbers in the Summary.Chlorophyll pigments absorb light which is the source of energy for photosynthesis.

Pentosephosphate is subsequently cleaved to glyceraldehyde-3-phosphate (GAP)andacetyl phosphate.
Photo provided by Flickr


Energy is used to convert GP into triose phosphate, ..

Steps 1 and 4 are catalysed by the same enzyme, aldolase. It first catalyses the reversible condensationof glyceraldehyde 3-phosphate with dihydroxyacetone phosphate, yielding fructose 1,6-bisphosphate (step 1); this is cleaved to fructose 6-phosphate and Pi by fructose 1,6-bisphosphatase in step 2. The reaction is strongly exergonic and essentially irreversible. Step 3 is catalysed by transketolase. Transketolase catalyses the reversible transfer of a 2-carbon ketol group (CH2OH-CO-) from a ketose phosphate donor, fructose 6-phosphate, to an aldose phosphate acceptor, glyceraldehyde 3-phosphate, forming the pentose xylulose 5-phosphate and the tetroseerythrose 4-phosphate. In step 4, aldolase acts again,combining erythrose 4-phosphate with dihydroxyacetone phosphate to form the seven-carbon sedoheptulose 1,7-bisphosphate. An enzyme unique to plastids, sedoheptulose 1,7-bisphosphatase, converts the bisphosphate to sedoheptulose 7-phosphate (step 5); this is the second irreversible reaction in the pathway. Transketolase now acts again, converting sedoheptulose 7-phosphate and glyceraldehyde 3-phosphate to two pentose phosphates in step 6. The pentose phosphates formed in the transketolase reactions - ribose 5-phosphate and xylulose 5-phosphate - are converted to ribulose 5-phosphate (steps 7 and 8), which in the final step (9) of the cycle is phosphorylated to ribulose 1,5-bisphosphate by ribulose 5-phosphate kinase. This is the third very exergonic reaction of the pathway, as the phosphate anhydride bond in ATP is swapped for a phosphate ester in ribulose 1,5-bisphosphate.

Sucrose & Starch Biosynthesis | Plant Phys Primer

In the first step of stage 2, the stromal 3-phospho-glycerate kinase catalyses the transfer of a phosphoryl group from ATP to 3-phosphoglycerate, yielding 1,3-bisphosphoglycerate. Next, NADPH donates electrons in a reduction catalysed by the chloroplast-specific isozyme of glyceraldehyde 3-phosphate dehydrogenase, producing glyceraldehyde 3-phosphate and Pi. Triose phosphate isomerase then interconverts glyceraldehydes-3-phosphate and dihydroxyacetone phosphate(Fig. 8.11). Most of the triose phosphate thus produced is used to ribulose 1,5-bisphosphate; the rest is either converted to in the chloroplast and stored for later use or immediately exported to the cytosol and converted to sucrose for transport to growing regions of the plant. In developing leaves, a significant portion of the triose phosphate may be degraded by glycolysis to provide energy.

Triose phosphate - Biology-Online Dictionary

The 3-phosphoglycerate formed in stage 1 is converted to glyceraldehyde-3-phosphate in two steps that are essentially the reversal of the corresponding steps in glycolysis, with one exception: the nucleotide cofactor for the reduction of 1,3-bisphosphoglycerate is rather than NADH (Fig. 8.11). The chloroplast stroma contains all the glycolytic enzymes except phosphoglyceratemutase.