The secreted proteins are packed inside the secretory vesicles which are pinched off from the Golgi apparatus.


- Secreted proteins are proteins that are produced by cells and then released into the extracellular space. These proteins play important roles in various biological processes such as cell signaling, immune response, and tissue repair.
- The process of packaging and transporting secreted proteins begins in the endoplasmic reticulum (ER), where the proteins are synthesized. After synthesis, the proteins enter the lumen of the ER and undergo modifications such as folding and addition of sugar molecules.
- From the ER, the proteins are transported to the Golgi apparatus. The Golgi apparatus consists of a stack of flattened membrane-bound compartments called cisternae. Each cisterna has a distinct composition and function.
- In the Golgi apparatus, the secreted proteins undergo further modifications, including sorting and packaging into secretory vesicles. These vesicles are small membrane-bound structures that bud off from the Golgi apparatus.
- The secretory vesicles contain the packaged secreted proteins and are then transported towards the plasma membrane of the cell. When they reach the plasma membrane, the vesicles fuse with it, releasing the secreted proteins into the extracellular space.
- Therefore, statement A is true. Secreted proteins are indeed packed inside secretory vesicles that are pinched off from the Golgi apparatus.

ER is absent in the red blood cells of mammals.


- The endoplasmic reticulum (ER) is a network of membrane-bound tubules and sacs present in eukaryotic cells. It plays a crucial role in various cellular processes, including protein synthesis, lipid metabolism, and calcium storage.
- However, mature red blood cells, also known as erythrocytes, do not contain a nucleus or most organelles, including the ER. This is because during their maturation process, these cells extrude their nucleus and most of their organelles to make space for the oxygen-carrying molecule, hemoglobin.
- The absence of the ER in red blood cells enables them to have a biconcave shape, which increases their surface area for efficient oxygen exchange.
- Therefore, statement B is true. ER is indeed absent in the red blood cells of mammals.

Both statement A and statement B are true. Secreted proteins are packed inside secretory vesicles that are pinched off from the Golgi apparatus, and the ER is absent in the red blood cells of mammals.