Advertisement Remove all ads

Describe the Process of Glycolysis with the Help of Schematic Representation. - Phases of Respiration: Glycolysis

Advertisement Remove all ads
Advertisement Remove all ads
Advertisement Remove all ads

Describe the process of glycolysis with the help of schematic representation.

Advertisement Remove all ads

Solution

Glycolysis consists of two major phases:
a. Preparatory phase and cleavage. b. Oxidative and payoff phase.

a. Preparatory phase and cleavage:
In this step, glucose molecule is activated by phosphorylation and then cleaved into two molecules of triose phosphates, namely 3-PGAL and DHAP. In the next step, only 3-PGAL participates and hence DHAP gets converted into 3-PGAL. Thus, 2 molecules of 3-PGAL are formed.
It includes the following reactions:
i. Phosphorylation I: A glucose molecule is phosphorylated to glucose 6-phosphate in presence of enzyme hexokinase. In this reaction, ATP supplies the phosphate and gets converted into ADP.
ii. Isomerisation: Glucose-6-phosphate is isomerised to fructose-6-phosphate in presence of enzyme phosphoglucoisomerase.
iii. Phosphorylation II: Fructose-6-phosphate is phosphorylated to fructose-1,6- diphosphate. Phosphate is supplied by ATP which gets converted to ADP. Reaction is catalyzed by enzyme phosphofructokinase.
iv. Cleavage: Fructose-1,6-diphosphate splits up into two inter-convertible compounds, i.e. Dihydroxy acetone phosphate (DHAP) and 3-phosphoglyceraldehyde (3-PGAL). Reaction occurs in presence of enzyme aldolase.
v. Isomerization : DHAP is isomerised into 3PGAL with the help of enzyme phosphotriose isomerase, thus two molecules of PGAL are obtained.

b. Oxidative and payoff phase:
In this phase, oxidation or removal of hydrogen takes place and then there is ATP generation.
i. Oxidative Phosphorylation: 3-PGAL undergoes oxidation and phosphorylation to form 1,3-diphosphoglyceric acid (1,3-DPGA). Hydrogen released combines with NAD to form NADH2. Phosphate is supplied for the reaction by phosphoric acid (H3PO4).
ii. ATP generation I / Dephosphorylation I: 1,3-diphosphoglyceric acid is dephosphorylated to 3-phosphoglyceric acid (3-PGA). Phosphate released combines with ADP to form ATP.
Reaction takes place in presence of enzyme phosphoglycero-kinase.
iii. Isomerisation: In presence of enzyme phosphoglycero-mutase, 3-Phosphoglyceric acid is isomerised to 2-phosphoglyceric acid.
iv. Dehydration: 2-Phosphoglyceric acid loses a water molecule to form phosphoenol pyruvic acid. The enzyme enolase catalyses the reaction.

v. ATP generation II / Dephosphorylation II: Phosphoenol pyruvic acid is dephosphorylated to pyruvic acid in presence of enzyme pyruvate kinase. Phosphate released combines with ADP to form ATP.

Concept: Phases of Respiration: Glycolysis
  Is there an error in this question or solution?
Advertisement Remove all ads
Share
Notifications

View all notifications


      Forgot password?
View in app×