Question

Which of the following provide mechanical support and shape to the cell?
A. Golgi Complex
B. Centrioles
C. Lysosomes
D. Endoplasmic reticulum

Answer 1

Endoplasmic reticulum is a double membranous organelle present in the eukaryotic organisms. The outer membrane of ER is continuous with a nuclear membrane. ER is classified into two types based on the presence or absence of ribosome on its outer surface. ER with ribosomes on its outer surface is known as rough ER whereas ER without ribosome is known as smooth ER.

Complete answer:
Two different types of Endoplasmic reticulum are found in eukaryotic cells, one is a rough ER and another is a smooth ER. Both the ER are involved in performing different functions inside the cell. Rough endoplasmic reticulum which possesses ribosomes on its outer surface is actively involved in synthesis of proteins. This is due to the fact that ribosomes are called protein factories due to their role in protein biosynthesis. Smooth endoplasmic reticulum is involved in synthesis of lipids. In animal cells, steroidal hormones are produced by smooth ER. Despite their usual functions, ER is also involved in post-translational modifications and transportation of proteins, lipids to their target location. This way ER stabilizes the cytoplasmic matrix and provides mechanical support to the cell. This in turn is responsible for the maintenance of the shape of the cell.

Hence the correct answer is option (D) Endoplasmic reticulum.

Note: Post-translational modifications occur inside the ER lumen, where the proteins formed are modified according to their function such as addition of carbohydrate side chain or phosphate group. After such modification, the modified proteins are packaged into secretory vesicles and transported to the golgi complex. Along with golgi complexes and lysosomes, ER is a part of the endomembrane system.