The Foundations of Metabolism

Energy Production: Glycolysis

Glycolysis is the initial breakdown of glucose, a fundamental process in cellular respiration. This simulation models the ten enzymatic steps involved, converting one molecule of glucose (C6H12O6) into two molecules of pyruvate (CH3COCOO). The primary goal is to capture and convert the potential energy within glucose into a usable form – ATP.

The key reaction driving this process is the oxidation of glucose. Each step involves substrate phosphorylation, where phosphate groups from ATP are transferred to intermediate molecules, ultimately generating a net gain of 2 ATP molecules per glucose molecule. The simulation accurately represents these energy transfers.

C6H12O6 → 2 CH3COCOO + 2 H2O + Energy (ATP)

Krebs Cycle: Fueling the Process

Following glycolysis, pyruvate enters the Krebs cycle (also known as the citric acid cycle). This cyclical pathway further oxidizes glucose-derived molecules, generating ATP, NADH, and FADH2. Each turn of the cycle involves a series of enzymatic reactions that release carbon dioxide.

The simulation tracks the conversion of acetyl-CoA (derived from pyruvate) through a series of redox reactions. Crucially, it models the production of 3 ATP molecules, 6 NADH molecules, and 2 FADH2 molecules per glucose molecule – representing the energy captured at each stage.

Acetyl-CoA + 3 O2 + 6 NAD+ + 8 ADP + 8 Pi → 2 CO2 + 6NADH + 8 ATP + 8H2O

Electron Transport Chain: Harnessing the Energy

The electron transport chain (ETC) utilizes the high-energy electrons carried by NADH and FADH2 to generate a proton gradient across the inner mitochondrial membrane. This gradient drives ATP synthesis via oxidative phosphorylation – the final stage of cellular respiration.

The simulation accurately models the series of protein complexes involved in transferring electrons, ultimately reducing oxygen to water (H2O). The movement of protons through ATP synthase creates a potential difference that powers ATP production. Approximately 30-34 ATP molecules are generated per glucose molecule.

NADH + H+ + O2 → NAD+ + H2O + ~32 ATP

Homeostasis and Feedback Mechanisms

Metabolic processes are tightly regulated to maintain homeostasis. The simulation incorporates feedback loops, such as the regulation of enzyme activity by product inhibition or allosteric control. These mechanisms ensure that energy production aligns with cellular demands.

The simulation demonstrates how disruptions in metabolic pathways (e.g., due to toxins or genetic mutations) can lead to imbalances and affect overall organismal health. Understanding these feedback loops is critical for comprehending biological regulation.

Frequently asked questions

Try it live

Everything above runs in your browser — open Michaelis-Menten Kinetics and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.