Cell Membrane Interactive

Start

What is a phospholipid?

What is a plasma membrane?

What is a plasma membrane composed of?

What passes through without help?

What passes through with help?

Phospholipids

The phosphate head is hydrophilic.

The Lipid tails are hydrophobic.

What do we call molecules that are both hydrophilic and hydrophobic?

Ampipathic

The individual phospholipids are not bonded together. They are held together simply because the tails hate water and are "hiding" from it, and the heads love water. If you threw a handful of phospholipids into a bucket of water, they would form a phospholipid bilayer all on their own!

Cell Membrane

Composition of the Cell Membrane

Things that pass without help:

Things that pass with help:

Some things are too big or the wrong kind to pass through the cell membrane easily. Think of the cell membrane like a very picky gatekeeper. Here’s what usually can’t get through on its own:

Info

Aquaporin

Transport Proteins

Facilitated Difusion

Ions (Charged Particles)

Large Molecules (charged and uncharged)

Water

If it's Large and Charged... it needs HELP to get through!

To get in or out, these things need special "helpers" like transport proteins or channels. It’s like needing a key to unlock the gate!

• Big molecules: Things like proteins or large sugars are too big to squeeze through the tiny openings in the membrane.
• Charged particles (ions): Small things like sodium (Na⁺) or chloride (Cl⁻) have an electric charge, and the membrane doesn’t like to let them through without help.
• Water-loving (hydrophilic) stuff: If something mixes with water, unlike oils and fats, it can have a hard time passing through.