USA Biology Olympiad (USABO) Practice Exam

Cells undergoing apoptosis exhibit which of the following characteristics?

1. Cells swell and burst

2. Reduction in cellular adhesion

3. Condensation of chromatin

4. Prominent cellular growth

The correct answer is: Condensation of chromatin

Apoptosis, often referred to as programmed cell death, is a highly regulated and organized process that plays a crucial role in development and maintaining cellular homeostasis. One of the hallmark features of cells undergoing apoptosis is the condensation of chromatin. During apoptosis, the chromatin, which is composed of DNA and proteins, condenses and becomes more tightly packed within the nucleus. This is often accompanied by nuclear fragmentation and the eventual breakdown of the cell into smaller, membrane-bound bodies called apoptotic bodies. This process is fundamentally different from necrosis, where cells typically swell and eventually burst, leading to inflammation and damage to surrounding tissues. Additionally, during apoptosis, there is a decrease in cellular adhesion as the cell prepares to break apart and disperse its components in a controlled manner rather than expanding in size. In terms of cellular growth, apoptosis leads to a decrease in cell number, contrasting with prominent cellular growth, which would indicate cell proliferation rather than cell death. Thus, the condensation of chromatin serves as a clear indicator of apoptosis and is a critical aspect of this programmed cell death mechanism.