Question

what feature of the plasma membrane makes it a unique membrane? Explain in detail how exchange of various materials take place across the plasma membrane

Answer 1

The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components —including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluidcharacter. Plasma membranes range from 5 to 10 nm in thickness.
The plasma membrane surrounding animal cells is where the exchange of substances inside and outside of cells takes place. Some substances need to move from the extracellular fluid outside cells to the inside of the cell, and some substances need to move from the inside of the cell to the extracellular fluid.

Some of the proteins that are stuck in the plasma membrane help to form openings (channels) in the membrane. Through these channels, some substances such as hormones or ions are allowed to pass through. They either are “recognized” by a receptor (a protein molecule) within the cell membrane, or they attach to a carrier molecule, which is allowed through the channels. Because the plasma membrane is choosy about what substances can pass through it, it is said to be selectively permeable.

Answer 2

Plasma membrane (also known as cell membrane) is a selectively permeable membrane which is present both in animal as well aa plant cell. It is the outermost covering of the cell that separates the contents of the cell from its external environment. It allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials.
Various materials take place across the cell membrane in two methods-
DIFFUSION- it is the spontaneous movement of a substance from a region of high concentration to a region of low concentration.
OSMOSIS- Osmosis is the passage of water from a region of high water concentration through a semi permeable membrane to a region of low water concentration.