Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

In which cellular structure does DNA replication take place?

1. Mitochondria

2. Nucleus

3. Ribosomes

4. Endoplasmic reticulum

The correct answer is: Nucleus

DNA replication occurs primarily in the nucleus of eukaryotic cells. The nucleus is a membrane-bound organelle that houses the cell's genetic material, including DNA. During the S phase of the cell cycle, the DNA within the nucleus is replicated to ensure that each daughter cell receives an accurate copy of the genome when the cell divides. The process of DNA replication involves several key enzymes and proteins, including DNA polymerases, which are responsible for synthesizing the new strands of DNA by using the existing strands as templates. This intricate process is tightly regulated and occurs within the environment of the nucleus, providing the necessary conditions and substrates for accurate replication. In contrast, other cellular structures mentioned in the choices play different roles. Mitochondria are responsible for energy production, ribosomes are involved in protein synthesis, and the endoplasmic reticulum functions in the synthesis of proteins and lipids as well as in the transport of these molecules. None of these structures are directly involved in the process of DNA replication, which is why the nucleus is the correct answer.