Mammoth Memory

What isn’t an organelle?

Membranes, cell walls and cytoplasm are not organelles, but are equally vital to the work and wellbeing of cells…

Membranes and cell walls

Plant cells have membranes and cell walls; animal cells only have membranes.

Cell walls are hard and thick; membranes are soft and thin.

 Image of a cell and where membrane can be found

The cell membrane, although forming a barrier, is soft and allows some substances in and out, playing a critical role in vital biological processes.

Image of a plant cell and magnification of cell walls

The cell wall is a plant cell’s rigid outer protection; the softer membrane is just inside the cell wall.

Cell walls are thick, membranes are thin comparison image


1.  You can see that the membrane is not a solid wall and lets things through if they are small enough.

2.  You can see that the membrane is soft.

3.  Remember that cell walls are only in plants.


The cytoplasm surrounds the organelles, filling all of the remaining internal space in the cell.

 This is the “jelly” that fills the cell.

Mnemonic showing cytoplasm surrounds organelles filling the voids in cells

Imagine the sight of a plasma TV (cytoplasm) filled with giant jelly babies. 

Below: Cytoplasm depicted within cell.

Image showing where cytoplasm can be found in cells

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