Q.6 An alternative to glycolysis pathway is
- (A) glyoxylate pathway
- (B) pentose phosphate pathway
- (C) citric acid cycle
- (D) gluconeogenesis
An alternative to glycolysis pathway is the pentose phosphate pathway, a parallel glucose oxidation route generating NADPH and ribose for biosynthesis. This SEO-optimized article resolves the MCQ: An alternative to glycolysis pathway is (A) glyoxylate pathway, (B) pentose phosphate pathway, (C) citric acid cycle, or (D) gluconeogenesis—essential for biochemistry and microbiology students studying metabolic networks.
Correct Answer: Option (B) Pentose Phosphate Pathway
The pentose phosphate pathway (PPP), also called the hexose monophosphate shunt, serves as an alternative to glycolysis by diverting glucose-6-phosphate for NADPH production in oxidative phase and pentoses in non-oxidative phase.
Active in liver, adipose, and erythrocytes, PPP supports fatty acid synthesis and nucleotide production, bypassing glycolysis’s pyruvate focus for reductive biosynthesis needs.
Explanation of All Options
These pathways interconnect but differ in function and context from glycolysis (glucose to pyruvate).
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(A) Glyoxylate pathway: Incorrect. This bypasses decarboxylations in plants/microbes (e.g., bacteria, fungi) for acetyl-CoA to carbohydrates, absent in mammals and not a direct glycolysis alternative.
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(B) Pentose phosphate pathway: Correct. Branches from glycolysis at G6P, yielding NADPH/ribose instead of ATP/pyruvate, universal in cytosol.
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(C) Citric acid cycle: Incorrect. Follows glycolysis via pyruvate in mitochondria for oxidation, not an alternative but downstream.
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(D) Gluconeogenesis: Incorrect. Reverses glycolysis for glucose synthesis from non-carbs, using similar enzymes reciprocally regulated.
Option Substrate/Product Location Relation to Glycolysis Correct/Incorrect (A) Glyoxylate Acetyl-CoA → succinate Glyoxysomes (plants/bacteria) TCA bypass Incorrect (B) Pentose phosphate G6P → ribose/NADPH Cytosol Parallel branch Correct (C) Citric acid Pyruvate → CO2/ATP Mitochondria Sequential Incorrect (D) Gluconeogenesis Lactate → glucose Cytosol/mito Reverse Incorrect Relevance in Biotechnology
PPP regulation links to your enzyme kinetics and microbial growth interests, influencing NADPH for fermentation redox balance and genetic engineering yields.
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