Internal respiration are: (PGI)
|A||Exogenic and anabolic|
|B||Exogenic and catabolic|
|C||Endogenic and anabolic|
|D||Cytochrome - C reductase involved|
Biological oxidation (catabolism) of food stuffs :-occurs in three stages
a. Primary metabolism (digestion)
In GIT, macromolecules are converted into small units i.e. carbohydrates into glucose, Lipids into fatty acids, and proteins into amino acids.
b. Secondary or Intermediate metabolism
These smaller units (eg. Glucose) are catabolized - and ultimately oxidized to CO -) producing
reducing equivalents (NADH or FADH via TCA cycle.
c. Tertiary metabolism or Internal Respiration or Cellular respiration
i. These reducing equivalents enter into electron transport chain, where energy is released. D
ii. Free energy (ΔG) detonates a portion of the total energy (=Enthalpy) change in a system that is
iii. available for doing work.
iv. Exergonic (=Exothermic) reaction:
v. In this →Free energy is released
G is negative
Reaction can occur spontaneously
eg. As definition in Internal Respiration energy is released and this reaction is Exergonic and
vi. There are three sites in ETC where free energy is released.
vii. Endergonic Reactions (=Endothermic reaction) : In this
Free energy is absorbed
ΔG is positive
An input of energy is required to drive the reaction Cyt-C-reductase →well known part of respiratory chain (ETC), and therefore internal respiration
In biological oxidation → free energy resulting from oxidation of food stuffs - 68% of free energy is
viii. captured in the form of ATP oxidative phosphorylation at the respiratory chain.
(i.e. Efficiency = 68%) and remaining free energy is liberated as =Exergonic)
“90% of O2 consumption in the basal state is mitochondrial, and 80% of this is coupled to
ix. ATP synthesis About 27% of the ATP is used for protein synthesis, and about 24% is used for Na+-
K+-ATPase 9% by gluconeogenesis, 6% by Ca+± ATPase, 5% by Myosin ATPase and 3% by