Cell Membrane
The membrane is a selective phospholipid bilayer.
About this topic
The cell membrane is a thin, flexible barrier surrounding the cell, made of a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails inside. Proteins embedded in it act as channels, pumps, receptors and markers, and cholesterol adds stability, described as the fluid mosaic model.
It is selectively permeable: small uncharged molecules like oxygen pass easily, while ions and large molecules need protein channels or transport. It controls what enters and leaves, and enables communication between cells.
The fluid mosaic model describes the membrane as a flexible sea of phospholipids in which proteins float like icebergs. Small non-polar molecules such as oxygen and carbon dioxide slip through the lipid core, while ions and large molecules need channel or carrier proteins. Cholesterol tucked between the lipids helps keep the membrane from becoming too stiff or too fluid as temperature changes.
Membranes matter in medicine: many drugs work by binding to receptor proteins on the surface, and diseases such as cystic fibrosis come from faulty channel proteins that move chloride ions. Students often picture the membrane as a rigid wall with holes; it is better imagined as a constantly moving, self-sealing film. Remember that selective permeability means some things pass freely, some need help and some are blocked.
Key ideas
- Hydrophilic heads, hydrophobic tails
- Proteins form channels
- Fluid mosaic model
Quick check
Use cases: where Cell Membrane helps
- Homework: review the key idea behind Cell Membrane before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Cell Membrane without notes.
- Visual learning: play with the interactive lab to see how Cell Membrane changes when you adjust its inputs.
- Teaching a friend: explain Cell Membrane in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Cell Membrane?
The membrane is a selective phospholipid bilayer.
What will I learn in Cell Membrane?
Hydrophilic heads, hydrophobic tails. Proteins form channels. Fluid mosaic model.
Is Cell Membrane part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Cell Membrane lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Cell Membrane?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.