Question

What happens in the investment phase of glycolysis?

Answer 1

Glycolysis:

1. It is a series of processes that results in the conversion of six-carbon glucose into two three-carbon keto-acids (pyruvate).
2. It generates free energy that may be used to synthesise high-energy molecules like ATP and NADH.
3. Glycolysis is divided into two phases: the energy-investment phase and the energy-yielding phase.

Investment phase of glycolysis:

1. The glycolysis energy-investment phase involves the investment of two ATP molecules, which leads to the creation of two molecules of glyceraldehyde phosphate.
2. Hexokinase uses one ATP to convert glucose to glucose-6-phosphate, which is then transformed to ADP.
3. Phosphoglucose isomerase is an enzyme that transforms glucose-6-phosphate into fructose-6-phosphate.
4. Phosphofructokinase uses one ATP to convert fructose-6-phosphate to fructose-1,6-bisphosphate, which is then turned into ADP.
5. Bisphosphate aldolase catalyses the process in which fructose-1,6-bisphosphate is converted into two three-carbon molecules: glyceraldehyde-3-phosphate and dihydroxyacetone phosphate (DHAP).
6. Triose phosphate isomerase is the enzyme that converts DHAP to glyceraldehyde-3-phosphate. Although this is a reversible process, DHAP is eventually depleted since glycolysis occurs in the following step.