In simple terms, photosynthesis is the conversion of carbon dioxide (CO2) to carbohydrate (CH2O). To do this two things are needed: energy to drive the reaction and a source of hydrogen.
The light reaction of photosynthesis produces two essential substances: ATP and NADPH. ATP provides the energy for the conversion of CO2 to CH2O, and NADPH provides the hydrogen.
The light reaction depends on groups of chlorophyll molecules, called photosystems, absorbing light energy. The energy is used to eject high energy electrons from the chlorophyll. The energy in the electrons is then used to make ATP and NADPH.
There are two photosystems, called photosystem I (PSI) and photosystem II (PSII), which work in sequence. (PSII comes before PSI in the sequence, but they were discovered and named in the reverse order!).
PSII absorbs light and emits a high energy electron. The energetic electron then passes down a series of molecules, called an electron transport chain (ETC), releasing energy as it goes (you can visualise it as a ball bouncing down a set of stairs, losing energy as it falls). The energy released is used to make the energy carrier compound ATP.
To replace the electrons lost from chlorophyll in PSII water (H2O) is split into hydrogen ions (H+), electrons (e-) and oxygen atoms (O):
H2O = 2H+ + 2e- + O
This is the source of the oxygen released by photosynthesis.
The second photosystem, PSI, also absorbs light and emits a high energy electron from chlorophyll. The energy in this electron is used to drive the synthesis of NADPH from NADP+ ,hydrogen ions (H+) and electrons (e-):
NADP+ + 2H+ + 2e- = NADPH + H+
The hydrogen ions needed for this come from the water which was split by PSII.
The electrons lost from the chlorophyll in PSI are replaced by the electrons ejected from PSII.
The result of all this is that light energy is converted into chemical energy in ATP, water is split to provide the hydrogen needed to make NADPH, and oxygen is released as a waste product.
The ATP and NADPH are then used in the light independent reaction (the Calvin cycle) to concert carbon dioxide into carbohydrate.
The process of renewing biological energy molecules like ATP and NADPHbe the harnessing of sunlight is called photosynthesis. The energy capture and conversion is mediated in the first step by chlorophyll in green plants.
Yes. ATP is used in the cell for quick energy by breaking the bond between the 2nd and 3rd phosphate group. NADPH is used to carry high-energy electrons. The energy is used to run the Calvin Cycle.
It is happening in firct phase. It is storing energy.
Light Reaction(s)
Light Reaction
through an electron transport chain
light energy
Light energy is converted into chemical energy. Photosynthesis is divided into two reactions (light reaction and light independent reaction) and they work together to make glucose, which can then be used by the cell.
A.T.P. and N.A.D.H are formed during light reaction.
The 'light reaction' portion of photosynthesis is driven by UV light from the sun.
Yes, this is the photosynthesis reaction.
through an electron transport chain
6CO2+6H2O+light energy-->C6H12O6+6O2 Chemical reaction of Photosynthesis
light energy
Light energy is converted into chemical energy. Photosynthesis is divided into two reactions (light reaction and light independent reaction) and they work together to make glucose, which can then be used by the cell.
photosynthesis
To provide ATP and NADPH to drive the next part of photosynthesis, the Calvin Cycle (AKA Dark Reaction, Light Independent Reaction). Light reactions also produce oxygen gas as a byproduct.
through an electron transport chain
The two reactions which occur during photosynthesis are light reaction and dark reaction. Light reaction takes place only in the presence of light. Dark reaction can occur with or without light.
An exothermic reaction is a reaction where heat or light energy is released. An example of this type of reaction is burning a candle.
Photosynthesis can be divided into two part: light reaction is the first stage of photosynthesis, occurring only in the presence of light, during which energy captured from light drives the production of ATP. dark reaction is the second stage of photosynthesis, not requiring light to occur, and during which energy released from ATP drives the production of organic molecules from carbon dioxide.
A.T.P. and N.A.D.H are formed during light reaction.
The first pathway of photosynthesis is the light reaction, which is the absorption of light energy from the sun by the chlorophyll in the plant. The pathway that follows this is the dark reaction or carbon fixation.