Chapter 22/23 Flashcards
what are the two parts of photosynthesis?
Light and dark reactions
what are light reactions?
reactions that transform light energy into ATP and biosynthetic reducing power, NADPH
synthesis of ATP
what are dark reactions?
light-independent reactions
The Calvin Cycle
what do dark reactions do?
they use the products of the light reactions to reduce carbon atoms from their fully oxidized state (CO2) to the more reduced state as a hexose
what do dark reactions produce?
carbohydrates
what is the carrier of electrons in biosynthetic pathways?
NADPH
what is the first step in light reactions?
Energy from light is used to boost electrons from a low energy state to a high energy state.
what happens once electrons are boosted to a high energy state in light reactions?
These electrons are used to reduce NADP+ to NADPH (for biosynthesis).
how is the proton-motive force generated and ATP synthesized in light reactions?
the electrons in the high energy state are used to generate a proton-motive force which drives the synthesis of ATP, by an electron-transport chain
where does the Calvin cycle take place?
in the stroma of chloroplasts
how is carbon dioxide gas trapped?
as an organic molecule, 3-phosphoglycerate
what happens to 3-phosphoglycerate in dark reactions?
it undergoes reduction reactions (using NADPH and ATP) to synthesize hexose sugars
where do light reactions occur?
thylakoids
why are thylakoids stacked?
to allow electron transport
which photosystem occurs first?
photosystem II
what does PSII do?
synthesize ATP and the H+ ion gradient by absorbing photons of light energy
what do quinones do?
they carry electrons to help produce H+
what does PSI do?
synthesize NADPH
transfer electrons to NADP+
glucose is highly ___
reduced
CO2 is highly ___
oxidized
how many stages does the Calvin Cycle have?
3
what is the first stage of the Calvin cycle?
Fixation of CO2 by ribulose 1,5-bisphosphate to form two molecules of 3-phosphoglycerate
what is the second stage of the Calvin cycle?
The reduction of 3-phosphoglycerate to hexose sugars
what is the third and final stage of the Calvin cycle?
The regeneration of ribulose 1,5-bisphosphate
