Question

define endoplasmin reticulum in short answer​

Answer 1

The endoplasmic reticulum (ER) is a large organelle made of membranous sheets and tubules that begin near the nucleus and extend across the cell. The entire structure can account for a large proportion of the endomembrane system of the cell. For instance, in cells such as liver hepatocytes that are specialized for protein secretion and detoxification, the ER can account for more than 50% of the total lipid bilayer of the cell. Similarly, the ER membrane system is particularly prominent in pancreatic beta cells that secrete insulin, or within activated B-lymphocytes that produce antibodies.

Answer 2

tubular structure which fills up the intracellular cavity .
and they are of two kinds .
a) rough endoplasmic reticulum which contains ribosomes inside it .
b) smooth endoplasmic reticulum which does not bear ribosomes inside ....

on one end endoplasmic reticulum is connected to the outer membrane of nucleus and on the other to plasma membrane