Which of the following processes and organelles account for the replacement of lipids and proteins lost from the plasma membrane?

• A. Endocytosis and Golgi
• B. Active transport and the rough ER
• C. Receptor-mediated endocytosis and smooth ER and Golgi
• D. Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi
• E. Exocytosis and smooth ER and rough ER

Answer: (E)

Verified step by step guidance

1. Understand the role of the plasma membrane: The plasma membrane is a dynamic structure that requires constant replenishment of its components, such as lipids and proteins, to maintain its integrity and function.
2. Identify the process of exocytosis: Exocytosis is a cellular process where vesicles containing lipids and proteins fuse with the plasma membrane, releasing their contents to the exterior and integrating new components into the membrane.
3. Explore the function of the smooth ER: The smooth endoplasmic reticulum (ER) is involved in lipid synthesis, which is crucial for replenishing the lipid components of the plasma membrane.
4. Examine the role of the rough ER: The rough ER is studded with ribosomes and is primarily responsible for the synthesis of proteins, including those that are destined for the plasma membrane.
5. Connect the organelles and processes: The smooth ER synthesizes lipids, the rough ER synthesizes proteins, and exocytosis facilitates the delivery of these newly synthesized components to the plasma membrane, ensuring its maintenance and repair.