(1) Glycolysis represents phase I of respiration.

(2) This pathway is common to both aerobic and anaerobic respiration.

(3) These reactions are completed in the cell cytoplasm (cytosol). Therefore, glycolysis is also called cytoplasmic respiration.

(4) Glycolysis involves a series of reactions in which a molecule of 6-C glucose is broken down in a step-wise manner into two molecules of 3-C pyruvic acid.

(5) Each step (reaction) is controlled by a specific enzyme and is reversible.

(6) Reactions in the glycolysis are anaerobic in nature,( i.e. they do not require molecular oxygen).

6-C Glucose is the most commonly used organic substrate for respiratory breakdown because

(i) It is most readily available.

(ii) It is soluble and can be easily transported and supplied..

Reactions of glycolysis (EMP pathway) involve :

(A) Phosphorylation of glucose (preparatory phase), isomerization to fructose-6-phosphate, and phosphorylation to fructose-I, 6-biphosphate.

(B) Cleavage of Fructose 1, 6 diphosphate to 2 3-C PGAL.

(C) Formation of 3-C pyruvic acid (end product of glycolysis). Various steps (intermediate reactions) in glycolysis are as follows.