Eukaryotic cell membranes all share the same basic phospholipid bilayer structure, but they vary mainly in the proteins embedded in them.

Core idea (the exam-style answer)

When textbooks or test questions ask, “In what way do the membranes of a eukaryotic cell vary?”, the intended answer is:

They vary in the specific proteins each membrane contains; certain proteins are unique to each membrane.

So among the common options, the correct one is:

  • “Certain proteins are unique to each membrane.”

All membranes:

  • Are made of amphipathic phospholipid bilayers.
  • Are selectively permeable to some degree.
  • Contain phospholipids in all major internal and plasma membranes.

What actually differs from one membrane (plasma membrane, ER, Golgi, mitochondria, etc.) to another is:

  • Which transporters, channels, and pumps they have
  • Which receptors and enzymes are present
  • The proportions of lipids and proteins that support those specific proteins’ functions

A quick illustration

  • Mitochondrial inner membrane: packed with proteins for the electron transport chain and ATP synthase.
  • Plasma membrane: rich in receptors, transporters, and adhesion proteins for communication and transport across the cell’s surface.
  • ER and Golgi membranes: contain proteins involved in protein and lipid synthesis and processing.

In all these cases, the basic lipid bilayer is similar, but the protein composition is what truly varies and gives each membrane its specialized role.

Meta description (SEO-style):
Learn in simple terms in what way the membranes of a eukaryotic cell vary, why membrane proteins matter, and how different organelles use unique protein sets to perform specialized functions.