Question

A) List, in order, the three enzymes that catalyze the highly regulated steps in glycolysis. (Don't just enter 1, 2, 3 for reaction numbers - give the reaction number based on the 10 steps of glycolysis.) Reaction # Enzyme Reaction # Enzyme Reaction # Enzyme B) For each of these reactions, name ONE allosteric regulator of the enzyme and whether that regulator inhibits or activates the enzyme. Reaction # allosteric regulator allosteric regulator Inhibitor or activator? Reaction # Inhibitor or activator? Reaction # allosteric regulator Inhibitor or activator? C) For each of these reactions, name the key enzym (that bypasses that step during gluconeogenesis. Glycolysis Reaction Gluconeogenesis enzyme Glycolysis Reaction Gluconeogenesis enzyme Glycolysis Reaction # Gluconeogenesis enzyme D) Now let's think about the role of fructose 2,6-bisphosphate and the role of glucagon in stimulating liver cells to make and secrete glucose to the blood. High glucagon would cause a(an) in the level of fructose 2,6-bisphosphate. (Write either increase" or "decrease in that blank.) What enzyme does fructose 2,6-bisphosphate ACTIVATE? E) OK, let's go back to the first of those glycolysis steps that you said was highly regulated. Using THERMODYNAMICS terms, what is it about this reaction that makes it a good point for regulation?

please answer all questions. thank you

Answer 1

a. The highly regulated steps of glycolsis are:

Reaction 1: Hexokinase

Reaction 2 : Phosphofructokinase

Reaction 10 : Pyruvate kinase

Hexokinase (Glucokinase in liver) Glucose Glucose 6-P ATP ADP Phosphofructokinase 1 Fructose 6-P Fructose 1,6-bis-P ATP ADP Pyruvate kinase Phosphoenolpyruvate Pyruvate ADP ATP

b. Reaction 1: allosteric regulator: glucose-6-phosphate- inhibits the hexokinase activity

Reaction 2: allosteric regulators:  PEP, citrate, and ATP - Inhibit the activity of the enzyme Phosphofructokinase

allosteric regulators: AMP and fructose-2.6-biphosphate- Activate the activity of the enzyme

Reaction 10: allosteric regulators: Fructose-2,6-biphosphate- activates

ATP and alanine inhibit the enzyme

c.

Glycolysis reaction	Gluconeogenesis enzyme
1	Glucose-6-phosphatase
2	Fructose biphosphatase
10	pyruvate carboxylase (PC) and phosphoenolpyruvate carboxykinase (PEPCK).

d. High glucagon would cause a decrease in the level of fructose 2,6 biphosphate as glucogon activates the enzyme fructose biphosphatase which converts the fructose biphosphate to fructose-6-phosphate.

Fructose-2,6 biphosphate activates the Phosphofructokinase while inhibits the activity of fructose-1,6biphosphatase

e. The regulatory steps of glycolysis have -$\Delta$G while all the other reactions taking place in the glycolysis have a +$\Delta$G. A negative -$\Delta$G means that the reaction is favoured in forward direction which is opposite in case of +$\Delta$G. Therefore, these 3 steps are known to be highly regulatory as they commit the substrate to undergo glycolysis.