X What is the name and function of the organelle indicated in the illustration above?
The Correct Answer and Explanation is:
Correct Answer:
Name: Rough Endoplasmic Reticulum (Rough ER)
Function: The rough ER is responsible for the synthesis and initial folding of proteins, especially those destined for secretion or for use in the cell membrane. It is termed “rough” because its surface is studded with ribosomes.
Detailed Explanation
The rough endoplasmic reticulum (rough ER) is a key organelle found in eukaryotic cells, and it plays a central role in the production and processing of proteins. It is a network of flattened sacs or tubules that extend from the nuclear envelope, and its surface is covered with ribosomes, giving it a “rough” appearance under a microscope. These ribosomes are the sites where amino acids are assembled into proteins based on genetic instructions carried by messenger RNA (mRNA).
One of the primary functions of the rough ER is to synthesize proteins that are to be exported from the cell, incorporated into the cell’s plasma membrane, or sent to an organelle called the lysosome. Once these proteins are synthesized by the ribosomes on the rough ER, they are threaded into the ER’s lumen where they may undergo modifications, such as folding into their correct three-dimensional shape or having carbohydrate groups attached (a process called glycosylation).
The rough ER also plays a role in quality control—misfolded or improperly assembled proteins are detected and either refolded or targeted for degradation. After initial processing, proteins are packaged into transport vesicles and sent to the Golgi apparatus for further modification, sorting, and shipping.
The close proximity of the rough ER to the nucleus allows for quick and efficient communication between the cell’s genetic material and the protein synthesis machinery. This proximity ensures that newly transcribed mRNA can rapidly reach the ribosomes for translation into proteins.
In summary, the rough ER is essential for the production of membrane-bound and secretory proteins, acting as a factory that ensures proteins are made, modified, and delivered correctly within the cell.
