bio ch 12

Here are the answers to your questions based on the provided notes on glycolysis:

• 3 Exergonic Reactions of Glycolysis
  Based on the note's emphasis on "key regulatory points," which are typically irreversible and highly exergonic steps, the three exergonic reactions are:

  1. Hexokinase: Converts glucose to glucose-6-phosphate.

  2. Phosphofructokinase-1 (PFK-1): Converts fructose-6-phosphate to fructose-1,6-bisphosphate.

  3. Pyruvate kinase: Converts phosphoenolpyruvate (PEP) to pyruvate.

• 5 Endergonic Reactions of Glycolysis
  
  

• Enzyme Regulated by Feedback Inhibition

  • Hexokinase is regulated by feedback inhibition, specifically by glucose-6-phosphate.

• Enzyme Regulated by Feedforward Activation

  • Pyruvate kinase is regulated by feedforward activation, specifically by fructose-1,6-bisphosphate.

• Level at which Fructose, Galactose, and Mannose Join the Glycolytic Pathway

  • Fructose: Enters the pathway as glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP).

  • Galactose: Enters the pathway as glucose-6-phosphate.

  • Mannose: Enters the pathway as fructose-6-phosphate.

• Regulation of PFK-1

  • Phosphofructokinase-1 (PFK-1) is a main point of regulation in glycolysis. It is:

    • Activated by: AMP and fructose-2,6-bisphosphate.

    • Inhibited by: ATP and citrate.

• Regulation of Pyruvate Kinase - **Regulation of Pyruvate Kinase** - **Activated by**: Fructose-1,6-bisphosphate (feedforward). - **Inhibited by**: ATP, alanine.