BIO... Flashcards
the process by which inorganic carbon from the atmosphere is assimilated into living organisms and converted into organic compounds.
CARBON FIXATION -
a plant enzyme which catalyzes the fixing of atmospheric carbon dioxide during photosynthesis by catalyzing the reaction between carbon dioxide and RuBP.
RuBisCo (Ribulose 1,5- bisphosphate carboxylase
oxygenase)
- use of an exergonic reaction
to fuel an endergonic reaction
COUPLING REACTION
is the gain of an electron by an atom or molecule.
REDUCTION
energy-carrying molecule that donates electrons and hydrogen atoms
NADPH
remaining G3P molecules regenerate RuBP
REGENERATION of RuBP (Ribulose biphosphate)
3-PGA
(3-Phosphoglyceric acid)
G3P
(Glycerol-3 phosphate)
- Chemical reactions during photosynthesis that
convert carbon dioxide and other compounds into
glucose, taking place in the Stroma. - refers to the light-independent reactions in
photosynthesis that take place in three key steps:
Calvin Cycle
3 Phases of Calvin Cycle
Phase 1: CARBON FIXATION
PHASE 2: REDUCTION
PHASE 3: REGENERATION OF RuBP
- (Riboluse 1,5 -bisphosphate carboxylase-oxygenase) catalyzes a reaction
between CO2 and RuBP, which forms a six-carbon
compound. - The six-carbon compound is too unstable that is
immediately converted into two three-carbon
compounds called 3-PGA (3-Phosphoglyceric
acid) (there will be 6 3-PGA with 18 carbons).
Phase 1: CARBON FIXATION
- This is the gain of an electron by an atom or
molecule. - ATP from LDR goes to the six 3-PGA so it needs
6 ATP. - ATP will undergo exergonic reaction to release
energy absorbed by PGA (endergonic) which will
make ADP + Pi - There will be 6 ADP and Pi that will go back to
LDR. - There is still not enough energy do it will get 6
NADPH from LDR since it has energy from the
photons, so it will transfer electrons and hydrogen
to each 3-PGS which forms 6-G3P. - This will become NADP+ and it will go back to
LDR. - ATP and NADPH use their stored energy to
convert the three-carbon compound, 3-PGA, into
another three-carbon compound called G3P
(glyceraldehyde-3-phosphate).
PHASE 2: REDUCTION
- remaining G3P molecules regenerate RuBP.
- There are 18 carbons in 6-G3P and 15 carbons in
RuBP, it only needs 15 carbons to make RuBP which means it needs 5 G3P only and there will be
1 excess G3P. - It needs to produce glucose which needs 6 carbons,
so it needs to perform Calvin Cycle again to gain
the remaining 3 carbons. - Some G3P molecules go to make glucose, while
others must be recycled to regenerate the RuBP
molecules. - 5 molecules of G3P are needed to create 3
molecules of RuBP. - 2 G3P molecules are needed to create glucose
molecules.
PHASE 3: REGENERATION OF RuBP
IMPORTANCE OF CALVIN CYCLE
Production of Glucose
- can be used by plants to perform cellular
respiration to produce more ATP. - Main energy source of the cell
- can be used for the
growth and repair of plant cells; Chain of glucose called cellulose is the main composition of plants,
cell wall.
Glucose (6-carbon sugar)
