Which of the following is known as the “guardian of the genome” –
**Core Concept**
The "guardian of the genome" is a term used to describe a protein responsible for maintaining the integrity of the genome by repairing DNA damage. This protein plays a crucial role in preventing mutations and maintaining genomic stability.
**Why the Correct Answer is Right**
The correct answer, p53, is a tumor suppressor protein that acts as a guardian of the genome. It functions by arresting the cell cycle in response to DNA damage, allowing for repair or inducing apoptosis if the damage is irreparable. p53 achieves this by binding to specific DNA sequences, transactivating genes involved in DNA repair and cell cycle arrest, and inhibiting genes involved in cell proliferation. The TP53 gene encodes for the p53 protein, which is a key regulator of the cell's response to DNA damage.
**Why Each Wrong Option is Incorrect**
* **Option A:** BRCA1 is a tumor suppressor protein involved in DNA repair, but it is not referred to as the "guardian of the genome".
* **Option B:** p21 is a cyclin-dependent kinase inhibitor that is a downstream target of p53, but it is not the "guardian of the genome" itself.
* **Option C:** BCL2 is an anti-apoptotic protein that is involved in regulating cell death, but it is not the "guardian of the genome".
**Clinical Pearl / High-Yield Fact**
p53 mutations are associated with an increased risk of developing various types of cancer, including breast, colon, and lung cancer. The TP53 gene is considered a tumor suppressor gene, and mutations in this gene can lead to loss of function, resulting in uncontrolled cell growth and cancer.
**Correct Answer:** C. p53