What is the end product of glycolysis ?

Answer

### Step-by-Step Solution

1. **Understanding Glycolysis**: Glycolysis is the first step of cellular respiration and occurs in the cytosol of the cell. It involves the breakdown of glucose into smaller molecules.

2. **Initial Conversion**: The process begins with glucose being converted into glucose 6-phosphate. This conversion requires the expenditure of 1 ATP molecule.

3. **Further Conversions**: The glucose 6-phosphate is then converted into fructose 6-phosphate, followed by the conversion into fructose 1,6-bisphosphate. This step also consumes another ATP molecule.

4. **Splitting the Molecule**: The fructose 1,6-bisphosphate is split into two three-carbon molecules: glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP). The DHAP can be converted into G3P, so we focus on G3P for the next steps.

5. **Energy Generation**: Each G3P molecule undergoes several transformations, ultimately leading to the production of 1,3-bisphosphoglycerate. During this transformation, 2 NAD+ molecules are reduced to form 2 NADH.

6. **ATP Production**: The 1,3-bisphosphoglycerate is then converted into 3-phosphoglycerate, generating 2 ATP molecules in the process. This is followed by further conversions that lead to the formation of phosphoenolpyruvate (PEP).

7. **Final Conversion**: The PEP is converted into pyruvate, which also generates another 2 ATP molecules.

8. **Net ATP Calculation**: In total, glycolysis produces 4 ATP molecules (2 from each of the two G3P molecules) and 2 NADH molecules. Each NADH can yield approximately 3 ATP when processed in the electron transport chain, leading to a total of 6 ATP from NADH. Therefore, the total ATP produced is 4 (from glycolysis) + 6 (from NADH) = 10 ATP.

9. **Accounting for ATP Used**: Since 2 ATP molecules were used in the initial steps, the net gain of ATP from glycolysis is 10 - 2 = 8 ATP.

10. **Final Product**: The end product of glycolysis is 2 molecules of pyruvate.

### Final Answer
The end product of glycolysis is **2 molecules of pyruvate**.

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