ASIS International (ASIS) Professional Certified Investigator Practice Exam

Where is DNA predominantly found in cells?

1. In the cytoplasm

2. In cells that do not contain a nucleus

3. In cells that contain a nucleus

4. In ribosomes

The correct answer is: In cells that contain a nucleus

DNA is predominantly found in cells that contain a nucleus, which are known as eukaryotic cells. The nucleus is an organelle that houses the cell's genetic material in the form of chromatin, which is organized into chromosomes. This containment allows for the regulation of gene expression and replication. In addition to the nucleus, eukaryotic cells also contain mitochondrial DNA located in the mitochondria, but the vast majority of genomic DNA resides within the nucleus. This structure provides protection and facilitates processes involving DNA, such as transcription and replication, by separating the genetic material from the cytoplasmic environment. Other options mention locations where DNA is either absent or significantly less prevalent. For example, in cells without a nucleus, typically prokaryotic cells, DNA is found in a more diffuse form throughout the cytoplasm. However, these cells lack the complex organization of DNA seen in eukaryotic cells. Therefore, eukaryotic cells, with their nucleus as the primary site for DNA, clearly indicate that option identifying cells that contain a nucleus is the most accurate choice.