"Last chapter" Flashcards
(23 cards)
How many molecule of CO2 go through one turn of the Calvin cycle and what happens to it
1 molecule is converted into one reduced carbon
how many reduced molecule of co2 (carbon) does it take to generate G3P (a three carbon molecule)
3 turns (3 co2 molecules need to be reduced
is G3P used by anabolic or catabolic pathways when generated by photosynthesis
anabolic
how many molecules of ATP and NADPH required in one turn of the Calvin cycle
9 ATP
6 NADPH
What is the first phase of the Calvin cycle (C3)
Fixation: fixing one carbon atom into one molecule of the 5 carbon sugar RuBP to produce two molecules of 3 - phosphoglycerate
what is the second phase of the Calvin cycle
Reduction: each molecule of 3-phosphoglycerate gets an additional phosphate added from the breakdown of ATP . this produces two molecules of 1, 3- biphosphoglycerate. Each of these is reduced (from NADPH) producing 1 G3P.
what is the third phase of the Calvin cycle
Regeneration: 5 of the 6 previously produced carbons are rearranged to to regenerate the single molecule of RuBP required for the next round of carbon fixation
how many molecules of G3P are used to regenerate 3 RuBP molecules
5
how many carbons are used in 3 RuBP molecules
15 carbons
when does the Calvin cycle generate a surplus G3P molecule
after three turns
how is the ATP and NADPH used in the Calvin cycle regenerated to be used again
it is regenerated by the light reactions
what is the most abundant protein within leaves
rubisco
what does rubisco do and why is he less efficient
can fix O2 and CO2, so sometimes fixes the wrong one (since there is so much O2 in the atmosphere
what is the C4 cycle
looks a lot like the citric acid cycle before going into Calvin cycle. Starts by producing PEP (3C), producing oxoacelate which is then reduced to malate. After being transported to the site of the Calvin cycle, the malate is oxidized to pyruvate, releasing CO2.
what is the main advantage of the C4 cycle
-it minimizes photorespiration because Co2 is generated by the enzymatic conversion of malate to pyruvate so the levels of co2 at the Calvin cycle site are high , effectively inhibiting the oxygenation reaction of rubisco.
-there is no loss of NADPH within the cycle
name three examples of C4 plants
- sugar cane
- corn
- grass/grain
what happens when O2 binds to the active site of rubisco
one of the products is a 2C compound that is exported from the chloroplast and actually requires the cell to consume ATP to convert to CO2, which is simply lost.
what is the starting point fir the synthesis of many organic molecules
G3P
what happens once G3P is converted to carbohydrates such as glucose and other monosaccharides
they enter may enter biochemical pathways that make disaccharides such as sucrose, polysaccharides such as starches and cellulose and other carbohydrates
what is the difference between C4 plants and CAM plants
C4 plants have spatial separation between the Calvin and C4 pathways(different locations), while CAM plants a temporal separation (run the cycles at different times)
give an example of a CAM plant
pineapple
what do the other pathways that consume G3P manufacture?
a diverse array of other molecules, including amino acids, fatty acids and lipids
where does the manufacturing of amino acids, fatty acids and lipids happen (plants)
they occur both within chloroplasts and in the surrounding cytosol
