Interesting facts on Physiology and Biochemistry



Floating respiration:

Carbohydrates and fats are used as respiratory substrates.

Protoplasmic respiration (Blackman):

Proteins are used as respiratory substrates.

The energy presents in one grand of different respiratory substrates is- Carbohydrates: 4.4 kcal or 18.4 kJ.

Fats: 9.8 kcal or41 kJ. Proteins: 4.8 kcal or 20 kJ.

Lohmann discovered ATP in 1929 and coined it in 1931.

Lipmann (1941):

Discovered ATP cycle.


To measure rate of respiration.

Viruses do not exhibit respiration.

Pasteur effect (Louis Pasteur):

A sudden change from anaerobic to aerobic respiration due to availability of oxygen.

α-Ketoglutaric acid:

An organic acid undergoes both dehydrogenation and decarboxylation and is First dicarboxylic acid formed during Kreb's cycle.

Mercury (Hg):

Used in anaerobic respiration experiments because it does not react with CO2.


Inhibits oxidative phosphorylation i.e., energy transfer inhibitor.


Wrote book "Cellular Respiration".

Glyoxylate cycle:

Takes place in seeds that contains tissues rich in fat and enable stored fat to be converted into carbohydrates. Enzymes for the cycle are present in glyoxysomes.

Cyanide resistant respiration is characteristic of plants and very useful for climacteric action (i.e., helpful in fruit ripening.)

Red or dark muscles:

Store myoglobin and hence oxygen for meeting the gap between supply and consumption during continuous activity.

White or pale muscles:

Do not store much myoglobin.

Lactic acid fermentation:

In muscles, pyruvic acid is reduced by NADH to form lactic acid which is catalysed by enzyme lactic dehydrogenase. Net gain is 2 ATP molecules per glucose molecule.


Enzyme complex present in yeast which helps in fermentation (zymosis)

Some of the energy liberated during respiration is wasted as heat.

Proton motive force:

Proton gradient + electric potential.

Dinitrophenol (DNP):

Inhibits ATP synthesis i.e., uncoupling of oxidative phosphorylation.

Mammalian RBCs are usually without mitochondria, so these show glycolytic pathway.

Cardiac muscles:

Fatigueless because have enzyme which can convert lactic acid into pyruvic acid to be used in aerobic respiration.

Robinson's ester:

Glucose - 6 - P.

Newber's ester:

Fructose- 6 - P.

Harden and Young ester:

Fructose -1, 6-DiP.


2 types i.e., Homofermentative (when only one end- product) and Heterofermentive (when two or more than two types of end-products).

Kostychev (1902):

Gave term anaerobic respiration.

Respiration is regulated by:

Regulatory enzymes of cell respiration (phospho fructokinase) ; inhibited by ATP build up while activated by excess of ADP; Allosteric inhibition or negative feedback by

Accumulation of NADH, and decreased in dark and by high sugar solution (osmotic effect).

Cut surfaces of apple become dark as tannins are oxidised to polyphenols in the presence of iron of knife, which is prevented by ascorbic acid (vitamin C) as it acts as anti-oxidant.

In bacteria, mesosomes are sites of ATP synthesis.