has ribosomes, site of most protein synthesis and transportation in cell
The endoplasmic reticulum is the organelle in a cell where most protein synthesis and transportation occur. It consists of rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). The rough endoplasmic reticulum is studded with ribosomes, which are responsible for protein synthesis.
The organelle you are referring to is the endoplasmic reticulum (ER). It is a network of tubules and flattened sacs located in the cytoplasm of a cell. The endoplasmic reticulum has two main forms: rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).
The RER is studded with ribosomes, which are responsible for protein synthesis. The ribosomes on the RER synthesize proteins that are destined for secretion, insertion into the cell membrane, or transport to other organelles. As the proteins are synthesized, they are threaded into the lumen of the RER, where they undergo further processing and folding.
Once the proteins are synthesized and processed in the RER, they are transported to their final destinations in the cell. This transportation process involves vesicles, small membrane-bound sacs. These vesicles bud off from the RER, carrying the newly synthesized proteins to various locations within the cell. The proteins may be transported to the Golgi apparatus, where further modifications and sorting occur, or they may be transported directly to the cell membrane or other organelles.
In summary, the RER, with its ribosomes, plays a crucial role in protein synthesis and transportation in the cell. The ribosomes on the RER synthesize proteins, which are then transported to their final destinations within the cell.
The organelle found in cells that has ribosomes and serves as the primary site of protein synthesis and transportation is called the endoplasmic reticulum (ER). The ER is a network of flattened sacs and tubules within the cell that is connected to the nucleus.
To understand why the ER is the site of protein synthesis and transportation, let me explain how proteins are produced and transported within cells:
1. Protein synthesis: Ribosomes, which are composed of RNA and protein, are responsible for building proteins. They read the genetic information stored in the cell's DNA and use it as a template to assemble amino acids into a chain, forming a protein. Ribosomes can be found free-floating in the cytoplasm or attached to the rough endoplasmic reticulum (RER).
2. Rough Endoplasmic Reticulum (RER): The RER gets its name from the ribosomes attached to its surface, giving it a rough appearance under a microscope. As the ribosomes synthesize proteins, they thread the newly formed protein chains through the outer membrane of the RER. The proteins are then folded into their proper three-dimensional shapes within the RER before they are further processed.
3. Protein transportation: Once the proteins are synthesized and properly folded in the RER, they are either destined for use within the cell or for export to other parts of the organism. To transport proteins to their target destinations, the RER has a network of membrane-bound sacs and tubules called the Golgi apparatus. The proteins bud off from the RER and are enclosed in vesicles that travel from the ER to the Golgi apparatus.
4. Golgi apparatus: The Golgi apparatus acts as a distribution center for proteins. It receives vesicles filled with proteins from the RER and modifies, sorts, and packages them for delivery to their final destinations. The proteins may undergo additional structural changes or receive specific chemical tags that help determine their proper targeting.
5. Transport vesicles: Once the proteins are processed in the Golgi apparatus, small vesicles bud off and carry the proteins to various destinations in the cell. Some vesicles deliver the proteins to other organelles, such as lysosomes or peroxisomes, while others transport proteins to the cell membrane for secretion outside of the cell.
In summary, the endoplasmic reticulum, particularly the rough ER, is the site of protein synthesis because it houses ribosomes that assemble amino acids into protein chains. The proteins synthesized by the ribosomes on the ER are then transported through the ER, Golgi apparatus, and vesicles to their final destinations within or outside the cell.