Chapter 17 (Energy for Biological Processes) Flashcards
What happens in the light-dependent stage of photosynthesis?
A) Energy from sun is used to create ATP
B) Hydrogen from water reduces coenzyme NADP to reduced NADP
What happens in the light-independent stage of photosynthesis?
Hydrogen from reduced NADP + CO2 is used to build organic molecules such as glucose, with energy supplied from ATP
What is the Calvin cycle?
The Calvin cycle is the reaction which occurs in the light-independent stage of photosynthesis. It produces organic molecules using products from the light dependent stage as well as CO2. The stages are as follows:
1) CO2 combines with RuBP with the help of the enzyme RuBisCO. Carbon from CO2 is fixed in this reaction (enters an organic molecule), (This step is called fixation)
2) An unstable 6 carbon molecule is formed and immediately breaks down, forming two 3-carbon GP molecules
3) GP is converted to triose phosphate (TP) using a hydrogen atom from reduced NADP and energy from ATP (both from the light dependent reaction), (This step is called reduction)
4) Most of TP is used to regenerate RuBP, with some being used to create organic molecules, (This step is called regeneration)
How is RuBP regenerated?
6 CO2 molecules must enter the Calvin cycle to create one glucose molecule. Therefore, 6 cycles = 12 TP molecules. 2 TP molecules are used to create glucose, while 10 TP molecules are used to create 6 RuBP molecules, regenerating the cycle.
