Page 71 - The Miracle in the Cell Membrane

Cell nucleus Golgi apparatus

Cell nucleus Microvillus
Nucleolus
Cell skeleton
Ribosomes Centrioles
Mitochondria
Smooth endoplasmic
reticulum Rough endoplas-
mic reticulum
Lysosome
Golgi apparatus
Cell
membrane

Centriole

Smooth endoplasmic reticulum Mitochondrion

Together with interior membranes surrounding many organelles inside
the cell, the cell membrane can be compared to the exterior wall of a
house. Though it separates the cell from the outside environment, the
cell membrane is not totally impassable. Rather, it operates as an
exceedingly sensitive control mechanism, permitting suitable sub-
stances to enter and depart, while preventing others from doing so.

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