Where are protein components of the extracellular matrix synthesized?
a. In the rough ER
b. In the Golgi apparatus
c. In the plasma membrane
d. In the extracellular layer itself

Verified step by step guidance

1. Understand the role of the rough endoplasmic reticulum (ER) in protein synthesis. The rough ER is studded with ribosomes, which are the sites of protein synthesis. Proteins destined for secretion or for use in the cell membrane are synthesized here.
2. Recognize that the Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or delivery to other organelles, but it is not the site of initial protein synthesis.
3. Consider the function of the plasma membrane, which serves as a barrier and communication interface for the cell, but is not involved in the synthesis of proteins.
4. Acknowledge that the extracellular matrix (ECM) is a network of proteins and other molecules outside the cell, providing structural and biochemical support to surrounding cells. However, the ECM itself does not synthesize proteins.
5. Conclude that the protein components of the extracellular matrix are synthesized in the rough ER, where they are initially assembled before being transported to the Golgi apparatus for further processing and eventual secretion outside the cell.

Key Concepts

Protein Synthesis in the Rough ER

The rough endoplasmic reticulum (ER) is a key site for protein synthesis, particularly for proteins destined for secretion or for use in the cell membrane. Ribosomes attached to the rough ER translate mRNA into polypeptide chains, which are then folded and modified within the ER lumen. This process is crucial for producing proteins that will be transported to the Golgi apparatus for further processing.

Role of the Golgi Apparatus

The Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or delivery to other parts of the cell. After proteins are synthesized in the rough ER, they are transported to the Golgi apparatus, where they undergo further modifications such as glycosylation. This organelle is essential for ensuring proteins are correctly processed and directed to their final destinations, including the extracellular matrix.

Extracellular Matrix Composition

The extracellular matrix (ECM) is a complex network of proteins and polysaccharides that provides structural and biochemical support to surrounding cells. Key protein components of the ECM, such as collagen and elastin, are synthesized inside the cell, primarily in the rough ER, before being secreted into the extracellular space. Understanding the synthesis and assembly of ECM components is crucial for comprehending how tissues maintain their structure and function.