VerifiedHint: The Endoplasmic reticulum is the largest organelle in a cell which has an extensive network of membrane-enclosed tubules and cisternae located near the nucleus and Golgi apparatus. It is the major site of protein synthesis and transport, protein folding, lipid and steroid synthesis, carbohydrate metabolism, and calcium storage.
Complete answer:
The endoplasmic reticulum is only present in the cytoplasm of the eukaryotic cells. It can be classified into two types- Smooth endoplasmic reticulum (absence of ribosomes) and Rough endoplasmic reticulum (presence of ribosomes).
Let us analyze the options one by one to find the correct answer.
Option A: The extensive network of endoplasmic reticulum is present all around the cell and it is also connected to the nuclear envelope. It's one of the major functions is to serve as the site for protein synthesis for secreted and integral membrane proteins. Hence, it behaves as a transport channel for proteins between the nucleus and cytoplasm and therefore, this is a correct statement.
Option B: This extensive network of tubular membranes is present all around the cell and thus it acts as an intracellular circulatory or transporting system. Hence, it transports materials between various regions in the cytoplasm and therefore, this is a correct statement.
Option C: The site of energy generation in a cell is Mitochondria where the Kreb cycle and chemiosmosis occurs and generates a large amount of energy in the form of ATP. Therefore, this statement is incorrect and hence this is the correct answer.
Option D: The endoplasmic reticulum is responsible for the synthesis of lipids (smooth) and proteins (rough). It provides an increased surface for enzymatic reactions and for the production of transmembrane proteins and lipids for most cell organelles. Hence, it can act as a site for many biochemical activities of the cell, and therefore, this is a correct statement.
Hence, the correct answer is option (C)
Note: The multi-functional nature of endoplasmic reticulum requires a myriad of proteins, unique physical structures, and coordination with and response to changes in the intracellular environment. Its cavity is well developed and thus acts as a passage for the secretory products.
