Question

Describe how the Pentose Phosphate pathway give organisms an advantage.

Answer 1

Significance of Pentose-Phosphate-Pathway:

(i) It oxidises Glucose-6-Phosphate to 6-Phosphogluconic acid which in turn is converted into pentose phosphates. In this pathway glucose-6-phosphate is directly oxidised without entering glycolysis, hence it is also known as Direct Oxidation Pathway or Hexose Monophosphate Shunt.

(ii) It provides alternative route for carbohydrate metabolism.

(iii) It generates NADPH molecules which are used as reductants in biosynthetic processes under conditions when NADPH molecules are not generated by photosynthesis. So, they are employed in non-photosynthetic tissues such as in differentiating tissues, ger­minating seeds and during periods of darkness.

(iv) It provides Ribose sugars for the synthesis of nucleic acids.

(v) It plays important role in fixation of CO₂ in photosynthesis through Ribulose-5-Phosphate.

(vi) It provides Erythrose-4-phosphate which is required for the synthesis of shikimic acid. The latter is precursor of aromatic ring compounds.

(vii) Pentose Phosphate Pathway, is special because no energy in the form of ATP (Adenosine triphosphate) is produced or used up in this pathway.This process is employed to produce the sugars that make up DNA and RNA. post glycolysis.