Proteins making up the cell membrane are called as extrinsic proteins and intrinsic proteins. *Proteins are synthesised in the ribosomes and are transported or secreted into endoplasmic reticulum to which ribosomes adhere. *Lipids are synthesised in the endoplasmic reticulum.

Synthesis of Lipids and Proteins in the Cell Membrane

Lipid Synthesis:
- Lipids that make up the cell membrane are primarily synthesized in the endoplasmic reticulum (ER) of the cell.
- The ER is a network of membranes where lipid molecules are assembled and then transported to other parts of the cell, including the cell membrane.
- The process of lipid synthesis involves enzymes and proteins that catalyze the formation of various lipid molecules, such as phospholipids and cholesterol.
- Once synthesized, these lipid molecules are then integrated into the cell membrane to maintain its structure and function.

Protein Synthesis:
- Proteins that are part of the cell membrane are synthesized in the ribosomes, which can be free-floating in the cytoplasm or attached to the endoplasmic reticulum.
- The synthesis of membrane proteins begins with the transcription of DNA into messenger RNA (mRNA) in the nucleus of the cell.
- The mRNA is then transported to the ribosomes where it serves as a template for the assembly of protein molecules through a process called translation.
- As the protein is being synthesized, it may undergo modifications such as folding and glycosylation to become functional membrane proteins.
- Once synthesized, these proteins are then inserted into the cell membrane through a process called membrane protein trafficking, where they are transported to their specific locations within the membrane.
In conclusion, lipids and proteins that constitute the cell membrane are synthesized in specific organelles within the cell, such as the endoplasmic reticulum and ribosomes, respectively. These processes are tightly regulated to ensure the proper structure and function of the cell membrane.