Conduction by plasma membrane-
(1) Carrier mechanism.
(2) Fixed pore mechanism
(i) Different types of protein molecules present in the cell membrane act as the carrier for some particular substances.
(ii) The protein made carrier fixes up the molecules of any substance, permeable to the cell with its own body.
(iii) Later the carrier along with the carried molecule enters the cell and releases it there.
(iv) Now, the carrier goes back to the outer end of the plasma membrane and repeats the same process.
Fixed pore mechanism:
(i) Protein molecules are present in the outer surface of the plasma membrane.
(ii) When the acceptable molecules of any substance come in contact with the carrier molecule, at once, the carrier molecule gets structural change and attains the shape of the pore and gradually moves to the inner side through the pore.
(iii) Just after reaching the inner surface of the membrane, the carrier molecule is released in the cytoplasm of the cell.
(iv) The cagier molecule returns to the initial stage through structural change molecule, change and gets ready to conduct one more new module.
This is the way how conduction occurs through plasma membrane
Fig: Translocation through the membrane, fixed pore mechanism