Question

does C2 cycle produce carbohydrates if yes could you explain me with reactions pls

Answer 1

The term “photorespiratory carbon cycle” should not be used for the C2 cycle, because that implies photorespira- tion is a separate process with separate CO2 and O2 pools. Rather, there is one process of photosynthetic carbon metabolism that is the sum of the C2 plus C3 cycles. Less informative nomenclature based on names of investigators, such as Calvin/Benson or Hatch/Slack cycles, is slowly disappearing. Topics related to the C2 cycle started at about the dates shown in Table 1, which also lists some events of my life. Metabolic pathways and enzymatic properties to support the C2 cycle are in the references. Our recent report of an O2 compen- sation point (Γ) during photosynthesis (10) has extended our viewpoint, but because it has not yet been extensively debated, those parts of this chapter addressing this are more speculative. A more extensive review of the O2 Γ may be found in a manuscript in preparation with Erwin Beck. For 50 years, investigators have studied glycolate and P-glycolate synthesis and its function, regulation, and inhibition. I am extending this with speculation on regulation of global CO2 and O2 concentrations. It will not be easy to overcome 150 years of dogma that photosynthesis is only O2 evolution and CO2 fixation (it is O2 and CO2 exchange), and the physiological impact that Rubisco is also an oxygenase. Most difficult of all is to understand that at the recent low atmos- pheric CO2 and high O2 about half of photosynthetic energy has been used by the C2 cycle.