Question

Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane? A. Exocytosis and smooth and rough ER B. Receptor-mediated endocytosis and smooth ER and Golgi C. Active transport and the rough endoplasmic reticulum D. Endocytosis and golgi E. Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi

Answer 1

The replacement of lipids and proteins lost from the plasma membrane is facilitated by exocytosis, a process involving both the smooth and rough ER as well as the Golgi apparatus. Vesicles carry new biomolecules to the plasma membrane, where they fuse and contribute to its composition. (Option A)

Step-by-step explanation:

The process that accounts for the replacement of lipids and proteins lost from the plasma membrane is exocytosis, which occurs in association with the smooth and rough Endoplasmic Reticulum (ER) and the Golgi apparatus. The rough ER is responsible for the synthesis of proteins, which may be destined for the plasma membrane. These newly synthesized proteins and lipids are then sent to the Golgi apparatus, where they are further modified, packaged, and sorted. Finally, vesicles that bud off from the Golgi apparatus fuse with the plasma membrane, replenishing its components through exocytosis.

The correct answer to the question is 'A. Exocytosis and smooth and rough ER', as this explains the process wherein newly synthesized lipids and proteins are transported via vesicles to the plasma membrane. The smooth ER plays a role in lipid synthesis, while the rough ER synthesizes proteins. Once these molecules are synthesized, they are packaged into vesicles that eventually fuse with the plasma membrane, adding to its constituents.