Describe the process of glycolysis. - AQA - A-Level Biology - Question 1 - 2021 - Paper 1
Question 1
Describe the process of glycolysis.
Worked Solution & Example Answer:Describe the process of glycolysis. - AQA - A-Level Biology - Question 1 - 2021 - Paper 1
Step 1
Phosphorylation of glucose using ATP
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Answer
The process of glycolysis begins with the phosphorylation of glucose. In this step, one molecule of glucose is phosphorylated using one molecule of ATP, resulting in glucose-6-phosphate. This modification helps to keep glucose inside the cell and prepares it for further breakdown.
Step 2
Oxidation of triose phosphate to pyruvate
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Next, the glucose-6-phosphate undergoes a series of transformations, eventually leading to the formation of two molecules of pyruvate. During these reactions, triose phosphate molecules are oxidized, which is critical for the overall energy yield of the process.
Step 3
Net gain of ATP
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Throughout glycolysis, a net gain of two ATP molecules is produced per molecule of glucose. This occurs due to the initial investment of two ATP molecules, followed by the production of four ATP molecules during the energy payoff phase.
Step 4
NAD reduced
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Finally, NAD+ is reduced to NADH during the oxidation of triose phosphate. This step is significant as the NADH produced can enter the electron transport chain to generate additional ATP under aerobic conditions.
