Steps of Photosynthesis - BiologyWise

Actually, photosynthesis is not a single process, but two, each with multiple steps.

Two steps of Photosynthesis? | Yahoo Answers

In respiration energy is released fromsugars when electrons associated with hydrogen are transported to oxygen (theelectron acceptor), and water is formed as a byproduct. The mitochondriause the energy released in this oxidation in order to synthesize ATP. Inphotosynthesis, the electron flow is reversed, the water is split (not formed),and the electrons are transferred from the water to CO2 and in theprocess the energy is used to reduce the CO2 into sugar. Inrespiration the energy yield is 686 kcal per mole of glucose oxidized to CO2,while photosynthesis requires 686 kcal of energy to boost the electrons from thewater to their high-energy perches in the reduced sugar -- light provides thisenergy.

Now we need to understand how cells can use the products ofphotosynthesis to obtain energy.

Steps of Photosynthesis Back to Top

(1) QB, which is more solvent exposed than QA, accepts the excited electron to form QB-. QA is now back in its oxidized state. Fully reduced QA can hold two electrons, which QA- is the "semiquinone" form. Even though two electrons will pass from the special pair through the entire cycle for one complete photosynthetic cycle, the QA never is in its fully reduced form.

The two stages of photosynthesis are treated in this figure as metabolic modules that take in ingredients and crank out products.

Water (H2O) is split in this process, releasing oxygen (O2) and hydrogen ions (H+). The electrons from the electron transport chain combine with these H+ ions and nicotinamide adenine dinucleotide phosphate ions (NADP+) to form adenosine triphosphate (ATP) and a reduced unit of NADP+, called NADPH (NADP plus an electron, or H). These energy storage forms, ATP and NADPH, are used to convert carbon dioxide (CO2) to build carbohydrates during the second phase of photosynthesis. Plants can then break down these carbohydrates to fuel their existence.

In essence, the chloroplast uses light energy to make sugar by coordinating the two stages of photosynthesis.


Stages of photosynthesis - YouTube

These intermediates are characterized by their resistance to so that they can operate in higher temperatures and dryer environments than . At right, the ranges of CO2 compensation points for the three types of plants are shown. These compensation points are the values at which the plants cease to provide net photosynthesis.

Photosynthesis occurs in two stages in a cell

In the first phase of photosynthesis, cellular protein pigments called chloroplasts are excited by light that propels them into high-energy states. The chloroplasts then transfer this energy through electrons to other protein complexes (read: several proteins stuck together). This group of proteins is called the electron transport chain. The proteins operate similarly to a group of dominoes: after the first one has been pushed, each protein transfers energy to each member along down the line.

A majority of plants use these steps in photosynthesis.

Photosynthesis is the first stage of energy flow through an ecosystem. You and all other animals on earth rely on the energy that plants store for life. But animals aren’t the only organisms that burn energy. Plants burn energy as they grow, too. In both plants and animals, the process of — which releases stored energy for use — occurs in the mitochondria inside each cell.

3 forms of photosynthesis are based on two pathways

Glycolysis itself yields two ATP molecules, so it is the first step of anaerobic respiration. , the product of glycolysis, can be used in to produce ethanol and + or for the production of lactate and NAD+. The production of NAD+ is crucial because glycolysis requires it and would cease when its supply was exhausted, resulting in cell death. A general sketch of the anaerobic steps is shown below. It follows Karp's organization.

Steps Involved in Photosynthesis

The problem of photorespiration is overcome in by a two-stage strategy that keeps CO2 high and oxygen low in the chloroplast where the Calvin cycle operates. The class of plants called and the also have better strategies than C3 plants for the avoidance of photorespiration.