Question

What is membrane biogenesis? Which cell organelle is responsible for it?

Answer 1

Hint: Biogenesis of membrane refers to synthesis of membrane. The organelle responsible for it occurs in three different forms, that are – cisternae, vesicles and tubules.

Complete Answer:
- In eukaryotic cells, a collection of membranous structures form an organised system that remains suspended in the cytoplasm. It is known as the endomembrane system. The chief components of the endomembrane system are – endoplasmic reticulum, nuclear envelope, golgi apparatus, cell membrane, vesicles, lysosomes and endosomes.
- The process of formation of cell membranes using lipids and proteins is known as membrane biogenesis. Membranes produced by the process of biogenesis divide the cell into different structural and functional sections.
- The cell organelle that is responsible for synthesis of cell membrane is Endoplasmic reticulum (ER). It is a complex network of interconnecting membrane bound tubes and vacuoles present in the cytoplasmic matrix. There are two types of ER – Agranular or smooth endoplasmic reticulum (SER) and granular or rough endoplasmic reticulum (RER). RER appears rough due to the presence of ribosomes attached to its surface. Ribosomes play a vital role in protein synthesis, therefore, RER are found in abundance in the cells which are actively involved in protein synthesis.
- Biogenesis of membranes is a multi-step process. The first step involves the synthesis of a basic membrane of lipid and intrinsic proteins and next steps include the addition of other components such as enzymes, specific sugars or specific lipids.
- The ER, especially SER contains the main phospholipid synthesizing and translocating enzymes that results in the formation of basic lipid membranes. The insertion of proteins into the newly synthesized membrane occurs through RER. Most of these proteins are formed by RER and then inserted into the membrane.

Note: The endoplasmic reticulum provides an ultrastructural skeletal framework to the cell and gives mechanical support to the cytoplasmic matrix.