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Photosynthesis Could Someone Give Me A Step By Step Procedure Of What Happens In Light Dependent

Photosynthesis (light dependent stage, light independent stage, calvin cycle)?

I always found this site extremely helpful when doing photosynthesis:

Photosynthesis (light dependent stage, light independent stage, calvin cycle)?

I always found this site extremely helpful when doing photosynthesis:

Can anyone explain the process of photosynthesis?

There was a rather complete explanation of the photochemistry
in Scientific American a few years back.
Check their archive.
(Probably more detail than you need.)
In a nutshell,: "Light energy converts water and CO2 into glucose."
You will see water drawn up the stem of the plant to feed this process,
but also to carry other essential dissolved minerals.
The excess water is lost through evaporation at structures in the
'skin' of the leaves.

Basic Questions on 1st and 2nd stage of photosynthesis?

Step 1: Photosystems
The light-dependent portion of photosynthesis is carried out by two consecutive photosystems (photosystem I and photosystem II) in the thylakoid membrane of the chloroplasts. The photosystems are driven by the excited chlorophyll molecules.

To begin photosynthesis, the chlorophyll molecule in photosystem II is excited by sunlight and the energy produced helps to break down a water molecule (H2O) into ½O2 (with electrons removed) and 2H+. The removed electrons are excited by the light energy. When the electrons prepare to come to their rest state, they go through an oxidative phosphorylation process and produces an ATP molecule.

As the electrons are coming to a resting state, they are excited again in photosystem I and raised to a even higher energy state. The excited electrons are then used to produce NADP+ + H+. The highly energetic NADPH molecule is then fed into the Calvin Cycle to conduct carbon fixation.

Step 2: Calvin Cycle
The second stage of photosynthesis, which takes place in the stroma of the chloroplast, can occur without the presence of sunlight. In this stage, known as the Calvin Cycle, carbon molecules from CO2 are fixed into glucose (C6H12O2). The reactions of the Calvin Cycle is as follows:

1. A five-carbon sugar molecule called ribulose bisphosphate, or RuBP, is the acceptor that binds CO2 dissolved in the stroma. This process, called CO2 fixation, is catalyzed by the enzyme RuBP carboxylase, forming an unstable six-carbon molecule. This molecule quickly breaks down to give two molecules of the three-carbon 3-phosphoglycerate (3PG), also called phosphoglyceric acid (PGA).

2. The two 3PG molecules are converted into glyceraldehyde 3-phosphate (G3P, a.k.a. phosphoglyceraldehyde, PGAL) molecules, a three-carbon sugar phosphate, by adding a high-energy phosphate group from ATP, then breaking the phosphate bond and adding hydrogen from NADPH + H+.

3. Three turns of the cycle, using three molecules of CO2, produces six molecules of G3P. However, only one of the six molecules exits the cycle as an output, while the remaining five enter a complex process that regenerates more RuBP to continue the cycle. Two molecules of G3P, produced by a total of six turns of the cycle, combine to form one molecule of glucose.

Could someone please help me with the "light dependant reaction/stage, in photosynthesis?

When chlorophyll a absorbs light energy, an electron gains energy and is 'excited'. The excited electron is transferred to another molecule (called a primary electron acceptor). The chlorophyll molecule is oxidized (loss of electron) and has a positive charge. Photoactivation of chlorophyll a results in the splitting of water molecules and the transfer of energy to ATP and reduced nicotinamide adenine dinucleotide phosphate (NADP).

The chemical reactions involved include:
condensation reactions - responsible for water molecules splitting out, including phosphorylation (the addition of a phosphate group to an organic compound)
oxidation/reduction (redox) reactions involving electron transfer

Photosynthesis is a two stage process.

1. The Light dependent reactions, a light-dependent series of reactions which occur in the grana, and require the direct energy of light to make energy-carrier molecules that are used in the second process:

light energy is trapped by chlorophyll to make ATP (photophosphorylation)

at the same time water is split into oxygen, hydrogen ions and free electrons:

2H2O 4H+ + O2 + 4e- (photolysis)

the electrons then react with a carrier molecule nicotinamide adenine dinucleotide phosphate (NADP), changing it from its oxidised state (NADP+) to its reduced state (NADPH):

NADP+ + 2e- + 2H+ NADPH + H+

T2. he light-independent reactions, a light-independent series of reactions which occur in the stroma of the chloroplasts, when the products of the light reaction, ATP and NADPH, are used to make carbohydrates from carbon dioxide (reduction); initially glyceraldehyde 3-phosphate (a 3-carbon atom molecule) is formed.


Photosynthesis is an important biochemical process in which plants, algae, and some bacteria convert the energy of sunlight to chemical energy. The chemical energy is used to drive synthetic reactions such as the formation of sugars or the fixation of nitrogen into amino acids, the building blocks for protein synthesis. Ultimately, nearly all living things depend on energy produced from photosynthesis for their nourishment, making it vital to life on Earth. It is also responsible for producing the oxygen that makes up a large portion of the Earth's atmosphere. Organisms that produce energy through photosynthesis are called photoautotrophs. Plants are the most visible representatives of photoautotrophs, but it should be emphasized that bacteria and algae also contribute to the conversion of free energy into usable energy

At what steps of Light-Dependent Reactions is ATP made?

The light-dependent reactions take place on the thylakoid membranes using four membrane-bound protein complexes called photosystem I (PSI), photosystem II (PSII), cytochrome complex (C) and ferredoxin complex (FD). In these reactions light energy is used to split water, oxygen is given off, and ATP and hydrogen are produced.

1. Chlorophyll molecules in PSII absorb photons of light, exciting chlorophyll electrons to a higher energy level and causing a charge separation within PSII. This charge separation drives the splitting (or photolysis) of water molecules to make oxygen (O2), protons (H+) and electrons (e‑):

2H2O O2 + 4H+ + 4e-

Water is a very stable molecule and it requires the energy from 4 photons of light to split 1 water molecule. The oxygen produced diffuses out of the chloroplast and eventually into the air; the protons build up in the thylakoid lumen causing a proton gradient; and the electrons from water replace the excited electrons that have been ejected from chlorophyll.

2. The excited, high-energy electrons are passed along a chain of protein complexes in the membrane, similar to the respiratory chain. They are passed from PSII to C, where the energy is used to pump 4 protons from stroma to lumen; then to PSI, where more light energy is absorbed by the chlorophyll molecules and the electrons are given more energy; and finally to FD.

3. In the ferredoxin complex each electron is recombined with a proton to form a hydrogen atom, which is taken up by the hydrogen carrier NADP. Note that while respiration uses NAD to carry hydrogen, photosynthesis always uses its close relative, NADP.

4. The combination of the water splitting and the proton pumping by the cytochrome complex cause protons to build up inside the thylakoid lumen. This generates a proton gradient across the thylakoid membrane. This gradient is used to make ATP using the ATP synthase enzyme in exactly the same way as respiration. This synthesis of ATP is called photophosphorylation because it uses light energy to phosphorylate ADP.

Diagram in link.

Photosynthesis and Cellular Respiration?

photosynthesis+6CO2 + 6H2O + Energy ® C6H12O6 + 6O2

1. Carbon dioxide in the air comes in through the stomates (those little holes in the leaf). 2. Water comes into the leaf from the roots. 3. Sunlight strikes the surface of the leaf and its energy is trapped by the chlorophyll. 4. The energy helps change part of the water to hydrogen (HYE-druh-jun) and oxygen (OX-uh-jun). 5. The hydrogen joins with the carbon dioxide to make food for the plant. 6. Oxygen gas comes out of the leaf through the stomates.

cellular respiration=C6H12O6 + 6O2 ® 6CO2 + 6H2O + Energy

Krebs Cycle
Electron Transport Chain

I want information about photosynthesis in microorganism?

I think you can visit (A free encyclopedia on net) to get information regarding photosynthesis. Basically, Photosynthesis is the method by which green plants containg chlorophyll produce food.

hotosynthesis (photo=light, synthesis=putting together), generally, is the synthesis of sugar from light, carbon dioxide and water, with oxygen as a by-product. It is arguably the most important biochemical pathway known; nearly all life depends on it. It is an extremely complex process, comprised of many coordinated biochemical reactions. It occurs in higher plants, algae, some bacteria, and some protists, organisms collectively referred to as photoautotrophs. This article summarizes some of the major aspects of the process and provides links to more detailed articles explaining the numerous technical details, and implications, involved.

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