, PLEASE USE THIS DOCUMENT AS A GUIDE TO ANSWER YOUR ASSIGNMENT
QUESTION 1
1.1. Explain why ATP is required for the preparatory steps of glycolysis.
ATP is required for the preparatory steps of glycolysis because these initial reactions involve the
phosphorylation of glucose and its derivatives. Specifically, in the first step, glucose is
phosphorylated by the enzyme hexokinase (or glucokinase in the liver) to form glucose-6-phosphate.
This process uses one ATP molecule. In the second step, glucose-6-phosphate is converted into
fructose-6-phosphate, which is then phosphorylated again by the enzyme phosphofructokinase using
another ATP molecule, forming fructose-1,6-bisphosphate.
These phosphorylation steps are essential because:
Activation of Glucose: Phosphorylation traps glucose within the cell by adding a negative
charge, preventing it from crossing the cell membrane and ensuring that it continues down the
glycolytic pathway.
Energy Investment: The phosphorylation steps increase the reactivity of the molecules,
making them more likely to undergo the subsequent reactions that lead to the production of
energy (ATP and NADH) later in glycolysis.
Though these steps consume ATP, the overall process of glycolysis results in the net production of
ATP, NADH, and pyruvate, which are crucial for energy production in cells.
QUESTION 1
1.1. Explain why ATP is required for the preparatory steps of glycolysis.
ATP is required for the preparatory steps of glycolysis because these initial reactions involve the
phosphorylation of glucose and its derivatives. Specifically, in the first step, glucose is
phosphorylated by the enzyme hexokinase (or glucokinase in the liver) to form glucose-6-phosphate.
This process uses one ATP molecule. In the second step, glucose-6-phosphate is converted into
fructose-6-phosphate, which is then phosphorylated again by the enzyme phosphofructokinase using
another ATP molecule, forming fructose-1,6-bisphosphate.
These phosphorylation steps are essential because:
Activation of Glucose: Phosphorylation traps glucose within the cell by adding a negative
charge, preventing it from crossing the cell membrane and ensuring that it continues down the
glycolytic pathway.
Energy Investment: The phosphorylation steps increase the reactivity of the molecules,
making them more likely to undergo the subsequent reactions that lead to the production of
energy (ATP and NADH) later in glycolysis.
Though these steps consume ATP, the overall process of glycolysis results in the net production of
ATP, NADH, and pyruvate, which are crucial for energy production in cells.
