Question

Plasma membrane is made up of
A. Protein
B. Lipid
C. Carbohydrate
D. Both A and B

Answer 1

Hint: The plasma membrane is the membrane found in all cells that separates the interior of the cell from the outside environment.

Complete Answer:
- The plasma membrane is the most thoroughly studied of all cell membranes. It is largely through investigation of the plasma membrane with respect to the newly evolving concepts of membrane structure.
- The cell membrane is composed of fatty acid based lipids and proteins.
- Membrane lipids are principally of two types, one is phospholipids and sterols. Both types share the defining characteristics of lipids. They dissolve readily in organic solvents, but in addition both have a region that is attracted to and soluble in water.
- Membrane proteins are also of two types, called as extrinsic proteins and other types are intrinsic proteins.
- The extrinsic protein is loosely attached by ionic bonds. They are calcium bridges to the electrically charged phosphorous surface of the bilayer.
- The intrinsic proteins are firmly embedded within the phospholipid bilayer. In general, membranes actively involved in metabolism contain a higher proportion of protein.
- The movement of a substance across the selectively permeable plasma membrane can be either ‘’passive’’ i.e. occurring without the input of cellular energy or “active” that it transport requires the cell to expend energy.

Therefore, the correct optimum is (D) both A and B.

Note: The main fabric of the membrane is composed of amphiphilic or dual- loving phospholipid molecules, amphiphilic having one surface consisting of hydrophilic amino acid and the opposite surface consisting of hydrophobic.