Membrane Permeability Calculator
Membrane Permeability Calculator is an educational tool designed to help students, researchers, and biology enthusiasts estimate the relative permeability of small non-electrolyte molecules across lipid bilayer cell membranes.
About the Tool
The Membrane Permeability Calculator uses the established solubility-diffusion model, a cornerstone of membrane biophysics. This model, supported by decades of peer-reviewed research, describes how molecules cross pure lipid bilayers through passive diffusion. Permeability (P) depends on a molecule's ability to partition into the hydrophobic core (via partition coefficient K) and its diffusion rate within the membrane (D), adjusted for membrane thickness (Δx).
Importance of Membrane Permeability
Membrane permeability is fundamental to cellular function. It determines how nutrients, waste, signaling molecules, and drugs enter or exit cells. In plants (relevant to agriculture), permeability affects nutrient uptake, herbicide efficacy, drought response, and stress tolerance. Understanding it helps in crop improvement, pesticide design, and understanding plant physiology. In medicine, it's critical for drug bioavailability and ADMET properties.
User Guidelines
- Enter the logP (octanol-water partition coefficient) — a standard measure of lipophilicity (available from PubChem, ChemDraw, etc.).
- Input the molecular weight (g/mol) to estimate diffusion.
- Adjust membrane thickness if needed (default 5 nm for typical eukaryotic cell membranes).
- Click "Calculate" — results appear instantly.
- Permeability is shown in cm/s — typical range for small molecules is 10⁻⁸ to 10⁻¹ cm/s.
When and Why You Should Use This Tool
Use this calculator to:
- Compare relative permeability of different molecules (e.g., nutrients, hormones, or agrochemicals).
- Understand how lipophilicity and size influence crossing the lipid bilayer.
- Educate students about passive transport in biology classes.
- Explore structure-activity relationships in early-stage research on plant/animal membranes.
Do NOT use for precise predictions in clinical or industrial settings — experimental validation is always required.
Purpose of the Tool
The main purpose is educational and illustrative: to demonstrate how scientific principles govern Membrane Permeability. By combining logP (solubility proxy) and molecular size (diffusion proxy), users see why hydrophobic small molecules cross easily, while large/polar ones do not (unless via channels/transporters). This tool promotes understanding of cell membrane selectivity.
This tool is provided by Agri Care Hub — your resource for agricultural and biological science tools.
Note: This calculator is based on simplified biophysical models (solubility-diffusion theory). Real membranes contain proteins, cholesterol, and vary by organism. Values are relative estimates for teaching purposes. For more, refer to literature on lipid bilayer permeation studies.
