AAMC FL Practice Exam

How are viral particles primarily internalized by cells?

1. Via exocytosis

2. Through receptor-mediated endocytosis

3. By active transport

4. Through endocytosis

The correct answer is: Through endocytosis

Viral particles are primarily internalized by cells through the process of endocytosis. This mechanism allows cells to engulf material from their external environment. When viruses approach a host cell, they typically bind to specific receptors on the cell surface. This binding triggers the invagination of the cell membrane, leading to the formation of an endocytic vesicle that encloses the viral particles. Endocytosis encompasses several pathways, including receptor-mediated endocytosis, which is a more specific form of endocytosis where the uptake of materials is mediated by the interaction of the cell's receptors with specific ligands, such as viral proteins. Although receptor-mediated endocytosis is a common and efficient way for many viruses to gain entry, the question asks about the broader category of how viral particles are internalized. Therefore, endocytosis, in general, is the more encompassing term that includes both receptor-mediated mechanisms and other forms of endocyctic pathways, thus making it the correct answer. The other options do not correctly represent the primary means by which viral particles enter cells. Exocytosis refers to the process in which materials are expelled from cells, while active transport requires energy to move substances against their concentration gradient, which is not the typical mechanism for viral entry