BIOL2771 WK4 P4

These flashcards cover the key concepts related to gluconeogenesis and its energetics.

Gluconeogenesis

An energetically expensive metabolic pathway that synthesizes glucose from non-carbohydrate precursors.

High energy phosphate groups

Six high energy phosphate groups are required to form one molecule of glucose from pyruvate, specifically four ATP and two GTP.

Free energy change of gluconeogenesis

The free energy change for gluconeogenesis is -16 kJ/mol.

Free energy change of glycolysis

The free energy change for glycolysis is -63 kJ/mol.

Irreversible steps

The process of gluconeogenesis has three bypass steps that are irreversible, similar to the irreversible steps of glycolysis.

Acetyl coenzyme A

Fatty acids are converted to acetyl coenzyme A, but cannot be converted to glucose in mammalian cells.

Glyoxylate cycle

A metabolic pathway found in plants, yeast, and bacteria that can convert acetyl coenzyme A to oxaloacetate, allowing the use of fatty acids for gluconeogenesis.

Pyruvate

A substrate that can be converted to glucose via gluconeogenesis and is a key intermediate in cellular respiration.

Glycerol

A small amount of glycerol derived from the breakdown of triacylglycerols can be used for gluconeogenesis.

Bypass steps in gluconeogenesis

Includes three key reactions that differ from glycolysis: conversion of pyruvate to phosphoenolpyruvate, fructose-1,6-bisphosphate to fructose-6-phosphate, and glucose-6-phosphate to glucose.

Energy cost of gluconeogenesis

Cells must invest a significant amount of energy to convert pyruvate to glucose to prevent loss of energy substrates.

Importance of gluconeogenesis

Essential in mammals during periods of energy demand, particularly in the liver, kidney, and small intestine for glucose supply.