The correct option is (c).
Explanation
The Endoplasmic Reticulum (ER) is a large network of membrane-bound tubes and sheets. It is classified into two types based on the presence or absence of ribosomes on its surface: Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER). These organelles play distinct roles in cellular synthesis and transport.
Statement-wise Analysis
- Statement 1 is Incorrect. The Smooth Endoplasmic Reticulum (SER) does not have ribosomes attached to its surface; this gives it a "smooth" appearance under a microscope. It is the Rough Endoplasmic Reticulum (RER) that has ribosomes attached to its surface, which gives it a rough texture.
- Statement 2 is Correct. The primary function of the SER is the manufacture of fat molecules, or lipids, which are essential for cell function. In contrast, the RER is primarily involved in protein synthesis due to the presence of ribosomes.
- Statement 3 is Correct. The lipids synthesized by the SER, along with proteins synthesized by the RER, are used to build the cell membrane. This process of building the cell membrane using synthesized lipids and proteins is known as membrane biogenesis.
Key Takeaway
Smooth Endoplasmic Reticulum (SER) lacks ribosomes and is responsible for lipid synthesis and detoxification of poisons (in liver cells). Rough Endoplasmic Reticulum (RER) possesses ribosomes and is responsible for protein synthesis.