01-02-2013, 02:19 PM
ELECTRON TRANSPORT CHAIN AND ATP SYNTHESIS
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INTRODUCTION:
An organism that lives in the presence of oxygen can extract a deal of energy from glucose by running it through two main metabolic pathway.
1.Glycolysis
2. Cellular respiration
By the end of these pathways, glucose has been completely oxidized and the cell has gained 36 molecules of ATP – a versatile energy carrier that fuels most kind of cellular work.
GLYCOLYSIS:
Glycolysis is a central pathway for the catabolism of carbohydrates in which the six-carbon sugars are split to three-carbon compounds with subsequent release of energy used to transform ADP to ATP.
Before glucose can be converted into ATP, it has be broken down into two pyruvate molecules. This process is known as glycolysis.
In glycolysis enzyme in the cystol splits into 2 molecules of pyruvate.
CELLULAR RESPIRATION:
Cellular respiration is the process by which the chemical energy is released and partially captured in the form of ATP.
Cellular respiration occurs in the mitochondria which is the power house of the cell.
Cellular respiration occurs in three main phases.
1.Pyruvate oxidation.
2.Citric acid cycle.
3.Respiratory chain.
Pyruvate oxidation:
Pyruvate oxidation occurs in the inner membrane of the mitochondria.
This process is a source of acetyl-CoA molecules for the citric acid cycle.
Pyruvate oxidation occurs in three easy steps.
1. The pyruvate is oxidized (it goes from 3C to 2C acetyl . CO2 is released as a result).
2.NAD+ is reduced to NADH
3. The pyruvate dehydrogenase complex attaches CoA to acetyl.
The total energy yield for this process is 2NADH's.
Respiratory chain:
This is the final phase of cellular respiration in which the cell make the bulk of its ATP. Although a few ATP molecules are formed in the glycolysis and the early stage of cellular respiration.
In glycolysis and cellular respiration, a cell breaks down a molecule of glucose and use its energy to form 36 molecule of ATP, an important cellular energy source.
Most of this ATP is generated in mitochondria during the final phase of cellular respiration, during which electron transport and ATP synthesis takes place.
ELECTRON TRANSPORT CHAIN AND ATP SYNTHESIS:
ETC and ATP synthesis takes in the mitochondria.
Mitochondria have two membranes:
1.Inner membrane
2.Outer membrane
These process takes place in the inner membrane of mitochondria.
INNER MEMBRANE: Contains the components required for the electron transport and ATP synthesis.
The two membranes are seperated by an acidic intermembrane space full of H2 ions (protons).
In the cellular respiration ,glucose is converted to CO2 and its H2 atoms are stripped off and donated to the molecules NAD+ and FAD to form NADH+H+ and FADH2.