roles of membrane proteins

Proteins - Proteins, which constitute about 10 to 12% of the cell contents, are macromolecules having a significant role in the metabolism of a cell. Proteins are polymers of amino acids. Each protein is a linear, unbranched, polypeptide molecule. T..

Cell membrane is present in both plant and animal cells. It is living, elastic and made of proteins and lipids (fats). Its function is to provide a mechanical barrier for the protection of the inner cell contents and to regulate the movement of molecules in and out of the cell...

It is a thin, elastic, selectively permeable membrane found internal to the cell wall. It is composed of phospholipids, proteins and polysaccharides. The plasma membrane is the site of most of the metabolic pathways. Certain structures are found associated with plasma ..

Plasma Membrane - The plasma membrane or cell membrane surrounds the cell contents in all types of cells. It is a multipurpose covering composed of phospholipids and proteins. fig. 16.4 - Cell Membrane Apart from the plasma membrane, an eu..

The cell membrane and the membranes of various cell structures exhibit the same structure and as such perform the same functions. However, the amount and arrangement of phospholipids and proteins varies in different cells and organelles. This variation accords a specif..

The molecular structure of cell membrane is still not clearly known. Several models have been proposed from time to time to explain its structure based on its physico-chemical properties. In the year 1935 Danielli and Dawson proposed that the cell membrane is made up of a lipid ..

The leucocytes are phagocytic and engulf the bacteria and other micro-organisms that attack the body cells. The lymphocytes secrete antibodies, that are special protein molecules that act against specific proteins present on the surface of the germs. These proteins ar..

Hormones are informational molecules. They are secreted in response to changes in the environment inside or outside the body. These are released into the extracellular fluid, where they are diffused into the blood stream. The latter carries them from the site of production to the site of action. Th..

1. Calcium is a component of calcium pectate, which is found in the middle lamella. 2. Acts as an activator of enzymes like ATP-ase, some kinases, phospholipases, a -amylase and succinate dehydrogenase. 3. Takes part in lipid metabolism. 4. Required in the maintenance of cell membrane. 5...

There is an increase in the amount of collagen proteins deposition in the intercellular spaces. This influences the permeability of cell membranes, affects the speed of diffusion of substances in and out and significantly influences the process of agei..