AEROBIOSIS

•AEROBIOSIS (Aerobic respiration) -

–a process of liberation of energy from respiratory substrate especially glucose which is broken down in a series of reactions where oxygen is required.

–consists of (a) glycolysis, (b) Krebs cycle and the  (c) electron transport system

–The energy liberated in certain reactions is used to form a bond between ADP and phosphate producing ATP. Such reactions are called phosphorylation.

Phosphorylation can be divided into two types : 

Substrate-level - phosphorylation  

Oxidative phosphorylation

Phosphorylation is the production of ATP through the formation of a bond between ADP and phosphate.  

Substrate-level phosphorylation is the formation of a bond between ADP and phosphate by directly transferring phosphate group from a high-energy molecule which has an unstable phosphate group. 

The phosphate group is transferred to ADP with the help of an enzyme transferase

Examples :

PGAL  +  ADP                           PGA  +  ATP

                                  Diphosphoglyceradehyde                       phosphoglycerate

GTP  +  ADP                           GDP  +  ATP

Creatine phosphate  +  ADP                           creatine  +  ATP

GTP = Guanosine triphosphate

Substrate-level phosphorylation has the following characteristics :

a)It is catalysed by a transferase (phosphorylase)

b)It does not require oxygen

c)It can occur in the cytoplasm, nucleus or mitochondria. 

AEROBIOSIS – Oxidative phosphorylation

•OXIDATIVE PHOSPHORYLATION

–The formation of ATP from ADP and phosphate in which OXYGEN IS REQUIRED.

–occurs inside the mitochondria, in the membrane of the cristae.

–involves the ELECTRON TRANSPORT SYSTEM