Question

describe different kinds of modification that occur to the cell membrane

Answer 1

Dietary lipids can modify the properties of cell membranes, including membrane fluidity and membrane permeability. The saturation and isomerization of dietary fatty acids may affect the pattern of fatty acids acylated to glycerol in phospholipids. Oxidized sterols may affect membrane properties directly by their insertion in the membrane or indirectly through their effects on lipid metabolism. The flow of calcium and other nutrients into the cells appears to be a major property affected by those changes in lipid composition of membranes and may be important in the onset of atherosclerosis. The factors that alter the character of the lipids in cell membranes should receive increased study in both in vitro and in vivo systems to clarify their role in diseases processes.

Answer 2

Answer:

Explanation:

The cell membrane, also known as the plasma membrane, is a double layer of lipids and proteins that surrounds a cell and separates the cytoplasm (the contents of the cell) from its surrounding environment. To perform some specialized functions, the cells undergo some modification of the cell membrane which are as follows:

1. Microvilli: Microvilli are microscopic cellular membrane protrusions that increase the surface area for diffusion and are involved in a wide variety of functions, including absorption, secretion, cellular adhesion, etc.

2. Junctional complex: Such changes occurs in the cell membrane between the cells.

a. Interdigitation- to increase surface area for exchange of material between two adjacent cells.

b. Tight junction-The extrinsic proteins in the plasmamembrane of two adjacent cells fuse to form a ‘spot weld’ like structure called tight junction. Their main function is adhesion of nearby cells.

c. Gap junction- Plasmamembrane proteins are modified in such a way that they form a tunnel between adjacent cells through which exchange of material can take place from one cell to another.

d. Desmosomes- Desmosomes are intercellular junctions that provide strong adhesion between cells. The plasmamembrane of adjacent cells secrete proteins into intercellular space that forms a cementing material. The cementing material is supported by tonofibrils that extend inside the cytoplasm of each cell providing additional strength.  

e. Terminal bars- Similar to desmosomes but without tonofibrils.

f. Plasmodesmata- They are found in plant cells. A narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells and allows communication/exchange materials between them.

3. Glycocalyx- The glycocalyx is a thick outer covering of the plasma membrane. It is composed of strands of sugars and proteins bound together. It can be a factor used for the recognition of the cell and/or it provides a protective coat for the cell under stress condition.

4. Sheath: Plasma membrane stretches to cover the base of a cilium or flagellum. This covering or stretch of plasmamembrane is called sheath.

5. Pores: Plasmambrane sometimes has tiny channel proteins through which different materials can pass through the cell, such channels are called pores. For e.g. Nuclear pores.