biology

What is the basic structure of all cell membranes?

Look up the fluid-mosaic model.

You have phospholipids which have their tails turned inwards due to their hydrophobic properties, and then the heads facing outwards due to their hydrophilic properties. This forms a bilayer.

Then you have various proteins on the outside (the mosaic part of the model) which act as receptors or transporters allowing substances/molecules in and out of the membrane.

(Bear in mind I did my A-Levels well over a year ago now, I hope that answers your question)