Question

1st attempt How do fermentation reactions in oxygen-starved muscle cells and anaerobically grown yeast cells differ? Choose one: Fermentation in muscle cells regenerates NAD and in yeast regenerates glucose. Fermentation in muscle cells generates NAD and in yeast generates NADH. Fermentation in muscle cells produces lactate and in yeast produces ethanol plus CO2. Fermentation in muscle cells produces ethanol plus CO2 and in yeast produces lactate. Fermentation in yeast cells includes glycolysis, whereas in muscle cells it bypasses glycolysis.

Answer 1

The correct answer is option 3, i.e. Fermentation in muscle cells produces lactate and in yeast produces ethanol + Carbon dioxide. The reason behind this is the anaerobic pathway taking place in muscle cells and yeast respectively.

The anaerobic pathway in Muscle cells is :

The anaerobic pathway in yeast is :

NADH NADH NAT NAD+ Glucose Pyruvate Lactate Fermentation

By seeing the pathway of fermentation, one can easily conclude that Lactate is being produced as the final product during fermentation of Glucose in muscle cells, while Ethanol + CO2 are the products of fermentation of Glucose in Yeast. The other four options are wrong since NAD+ is not getting regenerated anywhere (See first pathway). After getting recovered in first cycle, it is getting consumed in the next cycle in muscle cells. Secondly, yeast cannot regenerate Glucose since all these reactions are irreversible in nature. Thirdly, Glycolysis is occuring in both pathways since conversion of Glucose to Pyruvate is taking place in both cases.

APP+ Pi Acetaldehyde Gilecese Pyruvalle + NAP+ NADH Ethanol NADH Nhot

Therefore, only third option stands correct.

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