Universality of glycolysis: In which organisms is the pathway from glucose to 2 pyruvate found?

Introduction / Context:
Glycolysis is among the most ancient and conserved metabolic pathways. It provides ATP and metabolic intermediates in aerobic and anaerobic organisms alike, highlighting its central role in bioenergetics and biosynthesis.

Given Data / Assumptions:

• Glycolysis converts glucose to two molecules of pyruvate with net ATP and NADH production.
• Different taxa may localize or regulate glycolysis differently, but core reactions are retained.
• ATP yields and fates of pyruvate vary (fermentation vs. respiration).

Concept / Approach:
The Embden–Meyerhof–Parnas pathway (classic glycolysis) or closely related variants exist in bacteria, archaea, and eukaryotes. This universality suggests early evolutionary origin. While regulatory proteins differ, the enzyme set enabling glucose catabolism is ubiquitous because glucose is a common energy and carbon source.

Step-by-Step Solution:
Identify pathway steps shared across life forms.Note prokaryotic vs eukaryotic differences lie mainly in compartmentation and regulation, not presence/absence.Choose the inclusive answer: present in all living organisms.

Verification / Alternative check:
Comparative genomics shows homologs of glycolytic enzymes (e.g., GAPDH, enolase, pyruvate kinase) across domains of life.

Why Other Options Are Wrong:

• Animals only / eukaryotes only / yeast only / plants only: Each excludes vast groups (bacteria, archaea, protists) known to carry glycolysis.

Common Pitfalls:
Assuming organelle-based pathways (e.g., mitochondrial respiration) define universality; glycolysis is cytosolic and predates organelles.

Final Answer:
In all living organisms.