This will be a very "bare bones"
summary of photosynthetic chemistry:
Photosynthesis breaks down into a
Reaction and a
The light-dependent reaction uses, not too surprisingly,
light, but it also uses the water (actually, the hydrogen
part of the water, which releases the oxygen).
This part of photosynthesis shifts the light energy into a chain of
electrons which are used, in an electron-transport chain system similar to aerobic
respiration, to make a lot of energy-carrying molecules, including a lot of ATP.
These energy carriers drive the light-independent reaction,
which uses the carbon dioxide and actually makes the
glucose. For most plants on a typically sunny day,
when the sun goes down the light-dependent reaction stops,
but the backlog of energy carriers it has made may keep the
light-independent reaction going until the middle of the
interesting that on several levels, photosynthesis is a sort of
"mirror image" to
+ O2 energy to ATP >
CO2 + H2O
In aerobic respiration, the
glucose is broken "in half," fed through a cycle that breaks all of
the carbons away from each other, and sets up a chain of electrons
used to make energy carriers for the cells. Here, light sets
up the electron chain, which is used to make carriers which then
take single-carbon molecules and make larger carbon chains, with the
last step sticking "halves" together to make glucose. The real
details lose that forward-backward reflection, but you get the basic
In eukaryote cells,
photosynthesis happens entirely in chloroplasts, with some processes
happening on internal membranes and some dependent on differences
between the chemistry of the spaces.
A slightly more detailed explanation, with images.
More on the Light-Dependent Reaction.
More on the Light-Independent Reaction.
A graphic showing the steps, with sucrose the product here.
A movie showing the structures and processes working in a leaf cell.
The Photosynthesis Song.