RESPIRATION AND ENERGY TRANSFER

Respiration and Energy Transfer

Respiration: It is a catabolic process in which the complex food material, carbohydrate is broken down into the simpler form with the release of energy in the form of ATP.

Phosphorylation: Formation of ATP from ADP(adenosine diphosphate) and iP (inorganic phosphate) is called phosphorylation.

ATP: Adenosine triphosphate is known as the energy currency of the cell. upon hydrolysis, 1 ATP gives 7.3 Kcal.

Photophosphorylation: Light energy is converted into chemical energy in chloroplast                           synthesis of ATP by utilizing sunlight is called photophosphorylation.

Substrate-level Phosphorylation: It is direct Phosphorylation of ADP by transfer of a phosphate group from any suitable substrate. It occurs in the cytoplasm of the cells and the matrix of mitochondria.

Oxidative Phosphorylation: Oxidative Phosphorylation is Phosphorylation of ADP at the cost of energy released during oxidation of substrates like NADH₂ & FADH_2. This occurs on the inner mitochondrial membrane only.

Respiration: Respiration is a catabolic process wherein the complex organic substrate is oxidized to simple components to generate biological energy.

Anaerobic respiration: Anaerobic respiration is the cellular respiration that does not involve the oxygen at all.it is also called fermentation.

Glycolysis: Breakdown of glucose into two molecules of pyruvic acid is called glycolysis. This is a common step in anaerobic as well as aerobic respiration. It occurs in the cytoplasm of the cell.

The overall reaction of glycolysis:

          

Lactic acid fermentation:

         

Alcohol fermentation:  

        

Aerobic: Aerobic respiration involves molecular oxygen as final electrons acceptor                        which are liberated during oxidation of glucose.

Mitochondria: A powerhouse of the cell is called mitochondria. It is a site                                             of respiration.

Link reaction: This is an oxidative decarboxylation reaction.

          

     

            This is also a connecting link’ Reaction between glycolysis and Krebs cycle.

Kreb’s cycle/TCA cycle: Pyruvic Acid produced by glycolysis undergoes aerobic oxidation in the mitochondria matrix through the TCA cycle.

Amphibolic Pathway: Acetyl CoA or some other intermediates like a-ketoglutarate, oxaloacetate is used as precursors for the synthesis of fatty acids, glutamic acid and aspartic acid respectively. Hence Kreb's cycle can be correctly referred to as an ‘Amphibolic pathway’ i.e involving catabolism as well as anabolism.

Electron transport chain: Wherever the NADH₂ (NADH+H⁺) and FADH₂ are produced during glycolysis connecting link reaction and Krebs cycle, they are oxidised with the help of various electrons carries and enzymes.