Differentiate between rough and smooth endoplasmic reticulum. How is endoplasmic reticulum important for membrane biogenesis?
The following diagram give the structure of Smooth and Rough endoplasmic reticulum.
SER | RER |
It contains flattened sacs called cisternae. | It is mainly formed of vesicles and tubules. |
Smooth endoplasmic reticulum does not bear ribosomes over the surface of its membrane. | Rough endoplasmic reticulum possesses ribosomes attached to its membrane. |
It is engaged in the synthesis of glycogen, lipids and steroids. | It takes part in the synthesis of proteins and enzymes. |
Plasma membrane is made up of lipid and proteins. Endoplasmic reticulum is of two types-
(i) Rough endoplasmic reticulum with ribosomes attached on its surface for synthesizing proteins.
(ii) Smooth endoplasmic reticulum which is without ribosomes and is engaged in the synthesis of lipids.
Thus, endoplasmic reticulum acts as main site for synthesis of proteins and lipids which are needed for biosynthesis of plasma membrane. Hence, it is important for membrane biosynthesis.