Glycolysis Overview and Mechanism

Glycolysis Overview

• Glycolysis converts glucose to pyruvate
• Gluconeogenesis converts pyruvate back to glucose
• Glycolysis is a 10-step process
• Glycolysis generates energy (ATP and NADH)
• Glycolysis has two phases: preparatory and ATP-generating
• Glycolysis is tightly regulated to maintain energy balance

Glycolysis: Counting Electrons

• Glycolysis involves the transfer of electrons to NAD+ to generate NADH
• Glucose is oxidized to pyruvate
• 2x (C3-, C2+, C3+) = C2+
• 10-step process

Glycolysis: Counting Phosphates

• Glycolysis involves a series of phosphorylation reactions
• Two ATP are initially consumed
• A total of four ATP molecules are generated
• Net gain of 2 ATP molecules

Glycolysis: Two Parts

• Phase 1 (preparatory phase) consumes 2 ATP, and results in glucose breaking down into two 3-carbon molecules
• Phase 2 (ATP-generating phase) generates 4 ATP and occurs in the cytosol
• The overall yield of Glycolysis is 2 ATP and 2 NADH per glucose molecule
• Carbon & electrons are accounted for but the location of phosphate is not, thus, a concern in this step of Glycolysis

Glycolysis: Better Representation

• A detailed diagram outlining glycolysis steps & key components
• Phosphorylation, isomerization, cleavage, and phosphorylation are indicated as key features of glycolysis

"Pumps" of Glycolysis: Sites of Regulation

• A table summarizing reactions of Glycolysis
• Names of each reaction and steps, along with detailed enzyme that catalyzes that reaction
• Key regulatory steps of Glycolysis are highlighted (e.g., Hexokinase, Phosphofructokinase, Pyruvate Kinase)
• The table shows the equilibrium constant and the changing conditions as the reaction proceeds

G6P: Important Node

• Glucose 6-phosphate (G6P) is a crucial intermediate molecule
• G6P is a central crossroads in metabolism
• G6P leads to other pathways
• G6P has many different paths it can take depending on the body's needs

PFK First Committed Step

• PFK (Phosphofructokinase-1) is the first committed step in glycolysis
• PFK catalyzes the irreversible conversion of fructose-6-phosphate to fructose-1,6-bisphosphate
• This step is key to regulating glycolysis.

Glycolysis Makes ATP: ATP Inhibits Pump PFK

• Glycolysis yields ATP
• ATP is an allosteric regulator that inhibits PFK
• AMP activates PFK
• Fructose 2,6-bis-P is a stimulator for PFK

PFK Regulated by Energy Need: AMP & ATP

• AMP and ATP are important regulators of PFK
• High AMP indicates low energy levels, thus, PFK is needed to regenerate ATP
• High ATP indicates enough energy and PFK should be inhibited
• PFK activity regulated by AMP and ATP, as well as fructose-2,6-bisphosphate.

Okay, what do I need to know?

• Overall pathway, significant nodes (e.g., G6P, pyruvate)
• Principles of electron and phosphate counting
• Details & meaning of key regulatory steps, such as the "pumps".
• Activation and inhibition logic for key enzymes.

This quiz covers the essential processes of glycolysis, including its conversion of glucose to pyruvate and the energy production involved. Learn the steps of glycolysis, its two main phases, and the role of electron and phosphate transfer in energy metabolism.