Which of the following represents a correct ordering of the events that occur in the catabolism of glucose in the absense of `O_(2)` ?

Options

A. Glycolysis, TCA cycle, oxidative phosphorylation
B. Glycolysis, oxidative phosphorylation, TCA cycle
C. Oxidative phosphorylation, TCA cycle, glycolysis
D. Glycolysis, fermentation

Answer

To determine the correct ordering of events that occur in the catabolism of glucose in the absence of oxygen, we need to analyze the processes involved in anaerobic respiration. Here’s a step-by-step breakdown:

### Step-by-Step Solution:

1. **Glycolysis**: The first step in the catabolism of glucose, regardless of the presence or absence of oxygen, is glycolysis. This process occurs in the cytoplasm and breaks down one molecule of glucose (a 6-carbon compound) into two molecules of pyruvate (3-carbon compounds).

2. **Fermentation**: After glycolysis, in the absence of oxygen, the pyruvate produced is then converted into ethanol (in yeast) or lactic acid (in animals) through a process called fermentation. This process also occurs in the cytoplasm and allows for the regeneration of NAD+, which is necessary for glycolysis to continue.

### Correct Order of Events:
- **Glycolysis** → **Fermentation**

### Conclusion:
The correct ordering of events in the catabolism of glucose in the absence of oxygen is glycolysis followed by fermentation.

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