are both ER and secretory vesicles have double bilayer membrane
No, ER (endoplasmic reticulum) and secretory vesicles do not have double bilayer membranes.
The endoplasmic reticulum (ER) is an organelle found in cells that plays a crucial role in protein and lipid synthesis. It consists of a single phospholipid bilayer membrane. The ER has two main regions: the rough ER, which is studded with ribosomes and involved in protein synthesis, and the smooth ER, which lacks ribosomes and is involved in lipid metabolism and detoxification.
On the other hand, secretory vesicles are membrane-bound sacs that transport materials, such as proteins, from the Golgi apparatus to the cell membrane for secretion. Secretory vesicles are formed by budding off from the Golgi apparatus and are typically surrounded by a single phospholipid bilayer membrane. Once the secretory vesicle fuses with the cell membrane, its contents are released outside the cell.
So, while both the ER and secretory vesicles have membranes, the ER has a single bilayer membrane, whereas secretory vesicles also have a single bilayer membrane.