Question

explain about cell membrane.

Answer 1



It consists of a lipid bilayer with embedded proteins. The basic function of the cell membrane is to protect thecell from its surroundings. The cell membrane controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.

Answer 2

Answer :

Cell Membrane :-

• The detailed study about cell membrane took place in 1950s.
• The cell membrane is mainly composed of lipids and are arranged in a bilayer.
• The lipids are arranged to form cell membrane in such a way that their polar head is towards outer sides and hydrophobic tails towards the inner side.
• These lipid components mainly consists of phosphoglycerides.
• The cell membrane is also composed of proteins and carbohydrates.
• The ratio of proteins and lipids in the cell membrane varies from cell to cell.
• The membrane of erythrocytes in human beings consist of 52% of protein and 40% lipids.
• There are two types of proteins found in the cell membranes classifies based on ease of extraction.
• First one, peripheral proteins lie on the surface of membrane.
• The second one, integral proteins are partially or totally buried in the membrane.
• The model of cell membrane was proposed by Singer and Nicolson in 1972.
• This model was called as : Fluid Mosiac Model.
• According to it, the lipid had quasi-fluid nature that enabled lateral movement of proteins within the bilayer of membrane.
• This ability of moving within membrane is called fluidity.
• This nature is important from the point of other functions and works of the cell.
• The plasma membrane is involved in the transportation of molecules across it.
• The membrane is selectively permeable.
• The membrane allows some molecules molecules to move across the membrane without requirement of energy. Such transportation is referred to as passive transport.
• Some neutral solutes move across the membrane with the help of process of diffusion.
• Water also across membrane from higher concentration to lower concentration areas. (This movement is referred to as osmosis)
• The polar molecules require carrier protein of the membrane to transport across the membrane, because non polar lipid bilayer does not allow it to pass through it.
• Some ions move across membrane from lower concentration to higher concentration.
• Some of the molecules are energy dependent to transport through the membrane, and ATP is utilised in the transportation, then such transportation is termed as active transport.