Page 72 - The Miracle in the Cell Membrane
P. 72
The Miracle in the Cell Membrane
Cell mem branes are vital ly impor tant in hold ing cells togeth er
to form tis sue in multi-celled organ isms. Together with inte ri or
mem branes sur round ing the many organ elles with in the cell, the
over all cell mem brane can be lik e ned to the exte ri or walls sur -
round ing the rooms in a house. Though it sep a rates the cell's pro -
to plasm from the exter nal envi ron ment, the mem brane is not com -
plete ly imper me a ble, but func tions as an excep tion al ly sen si tive
con trol mech a nism, allow ing suit a ble sub stan ces to enter and
leave, while pre vent ing oth ers from enter ing. For instance, it
admits food sub stan ces and expels waste pro ducts. In addi tion it
trans mits chem i cal and elec tri cal sig nals that induce the cell to pro -
duce pro teins or else to divide in two. Therefore, the cell mem-
brane is one of the most vital organelles of the cell.
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