Some of the main stages of cellular reaction in plants are as follows:
(a) Glycolysis (b) Transition Reaction (c) The Krebs cycle (d) Electron Transport Chain.
Plants used to produce energy through the process of photosynthesis as well as cellular respiration. Cellular reaction in plants is totally opposite to photosynthesis, and more importantly, it does exist in plant life.
There are four stages of cellular reaction in plants – glycolysis, transition reaction, the Krebs cycle, and electron transport chain.
The first stage – glycolysis, is the process wherein the glucose obtained from the food is chemically modified to form compound private. This process occurs in the cytosol of the cell and is carried out in the absence of oxygen. During this process, energy is released from glucose compounds in the form of 2 NADH molecules and 2 ATP molecules.
(b) Transition Reaction:
The second stage-Transition reaction, also known as private decarboxylation, wherein pyruvate is decarboxylated and added to Coenzyme A (CoA) in order to form Acetyl CoA. It is an important stage in the cellular respiration process as it forms a link between the metabolic pathways of glycolysis and the Krebs cycle.
(c) The Krebs cycle:
The next stage, the Krebs cycle comprises a series of steps which oxidize the Acetyl CoA molecule. Unlike glycolysis, the Krebs cycle requires oxygen for functioning. This aerobic process is catalyzed by enzymes. 2 complete turns of the Krebs cycle produce 4 carbon dioxide molecules, 6 NADH molecules, 2 ATP molecules and 2 FADH2 molecules.
(d) Electron Transport Chain:
The last stage is the electron transport chain, which produces the remaining 32-34 ATP. The chain is made up of electron-carrying proteins, based at the membrane of the mitochondrion. These proteins transfer electrons from one self to another. These electrons are finally added to oxygen, which is the final electron acceptor, along with the protons which leads to formation of water.
In this process, ATP is produced by proton motive force, a store of potential energy created by the gradient that is formed when the protons move across the biological membrane. In simple words, electron transport chain triggers a gradient though which ATP is produced in a process known as chemiosmosis. During photosynthesis the plant utilizes the energy from the Sun and stores it in the form of bonds of glucose molecules.
In course of cellular respiration, the glucose molecules stored in the plants are broken down to obtain energy in the presence of oxygen. The plant can also produce ATP in the absence of oxygen in a process which is called as fermentation. However, it’s not as efficient as cellular respiration, and therefore is not considered so important.