Question

Cell membrane is
a. Unilaminar
b. Bilaminar
c. Trilaminar
d. Quadrilaminar

Answer 1

Hint: Cell membrane is also called a cytoplasmic membrane or plasma membrane, where it protects the interior of the cell or cell organelles from the external environment.

Complete answer:
Functions of the cell membrane include:
- The cell membrane is attached to the cytoskeleton, and it gives shape to the cell.
- Cell membrane plays a role in intercellular connection, to connect or hook with other cells with the help of proteins.
- It has a role in signal transduction, where it transmits a signal from internal to exterior.
- It has a role in enzyme activity.
- And transport of various substances, in and out of the cell.

Membrane model of the cell.
- The cytoplasmic membrane consists of bilayer phospholipids.
- These phospholipids consist of hydrophilic heads and hydrophobic tails.
- The arrangement of the phospholipid layer is in such a way, each phospholipid layer has heads and tails, where each phospholipid layer is formed in such a way, where, each layer hydrophilic tails are lined up together and faced towards the other phospholipid layer arranged in the same way.
- So both layer phospholipids tails are faced with each other and at the same time, the hydrophobic heads of both layers are sandwiched between these hydrophilic tails of 2 layers of phospholipids.
- So it appears as, a single layer of hydrophilic tails, facing outside and a single layer of hydrophilic tails facing inside and a layer of hydrophobic heads of both layers which are between these two tail layers, usually appear as the third layer, so the cell membrane is called as trilaminar.

Hence, the correct answer is option (C).

Note: So many theories are proposed to explain the cell membrane, among them Trilaminar theory was proposed by Danielle and Daveson, where they told that along with the bilipid layer, there is a protein layer that is added up and another theory was proposed by Robertson called unit membrane model, and other was Micellar theory by Hoffman.