8.2.1 Oncogenes and Tumor Suppressor Genes

• Proto-oncogenes, when mutated, transform into oncogenes that promote uncontrolled cell growth.

  True
• Arrange the following oncogenes in order of their roles in the cell cycle:

  1️⃣ MYC: Accelerates G1 phase to S phase transition

  2️⃣ RAS: Activates cell proliferation pathways

  3️⃣ CCND1: Initiates cell cycle entry and G1 progression
• Point mutations are single nucleotide changes that alter the protein structure and function
• The MYC oncogene acts as a transcription factor that promotes cell growth and proliferation, accelerating the G1 phase to the S phase transition.
• What happens to tumor suppressor genes when they are mutated or inactivated?

  Loss of tumor suppression
• Order the key functions of tumor suppressor genes:

  1️⃣ Cell growth regulation

  2️⃣ DNA repair

  3️⃣ Apoptosis induction
• What is the role of proto-oncogenes in normal cells?

  Regulate cell growth
• Proto-oncogenes code for proteins that control processes such as cell proliferation, differentiation, and apoptosis.


  True
• What is viral insertion, and how does it contribute to oncogene formation?

  Virus inserts DNA into host
• Oncogenes influence the cell cycle by accelerating its progression through critical checkpoints and inhibiting apoptosis.
• Oncogenes disrupt normal cell cycle regulation, contributing to tumor formation.


  True
• What role do oncogenes play in cell division and tumor formation?

  Disrupt normal cell cycle
• RAS is a signal transduction protein that activates cell proliferation pathways.

  True
• ERBB2, also known as HER2, is a receptor tyrosine kinase
• What happens to tumor suppressor genes when they are mutated or inactivated?

  No longer suppress tumors
• RB is a tumor suppressor gene that blocks the transition from G1 to S
• Mechanisms by which tumor suppressor genes can become inactivated:

  1️⃣ Point Mutations

  2️⃣ Chromosomal Deletions

  3️⃣ Epigenetic Silencing

  4️⃣ Loss of Heterozygosity (LOH)
• What type of cancer is associated with the deletion of the RB gene?

  Retinoblastoma
• Match the characteristic with the correct type of gene:

  Function of proto-oncogenes ↔️ Regulate cell growth and division

  Effect of mutated tumor suppressor genes ↔️ Inability to suppress tumors

  Effect of mutated proto-oncogenes ↔️ Uncontrolled cell growth
• What is the normal function of tumor suppressor genes in the cell cycle?

  Suppress tumor formation
• What role do proto-oncogenes play in normal cells?

  Regulate cell growth
• Proto-oncogenes transform into oncogenes when they are mutated or overexpressed.


  True
• What is a point mutation, and how does it contribute to the transformation of proto-oncogenes into oncogenes?

  Single nucleotide change altering protein structure
• Which proteins repair double-strand breaks in DNA?

  BRCA1/2
• Point mutations in the p53 gene are the most commonly mutated in cancer
• What is an example of a chromosomal translocation that transforms a proto-oncogene into an oncogene?

  Philadelphia chromosome in CML
• Tumor suppressor genes are normal cellular genes that suppress uncontrolled cell proliferation
• Which tumor suppressor gene blocks the transition from G1 to S phase in the cell cycle?

  RB
• The p53 gene triggers apoptosis in response to irreparable DNA damage.


  True
• Oncogenes, when mutated, promote uncontrolled cell growth, while tumor suppressor genes suppress tumor formation
• Mutations in the p53 gene are the most commonly observed in cancer
• Oncogenes drive uncontrolled cell growth, while tumor suppressor genes prevent it when functioning correctly.


  True
• Epigenetic silencing involves methylation or histone modifications that repress transcription of the tumor suppressor gene.

  True
• What are proto-oncogenes and their role in the cell?

  Normal cellular genes regulating growth
• Match the tumor suppressor gene with its function:

  p53 ↔️ Master regulator of DNA repair

  RB ↔️ Inhibits cell cycle progression

  BRCA1/2 ↔️ Repairs DNA double-strand breaks
• Proto-oncogenes can become oncogenes through mechanisms such as point mutations, gene amplification, or chromosomal translocations
• Gene amplification leads to overexpression of the affected gene, which can transform a proto-oncogene into an oncogene.


  True
• Oncogenes influence the cell cycle by accelerating its progression and inhibiting apoptosis
• Proto-oncogenes are normal cellular genes that regulate cell growth and division
• Match the mutation mechanism with its example:

  Point Mutations ↔️ Ras protein mutations in bladder cancer

  Gene Amplification ↔️ N-myc amplification in neuroblastoma

  Chromosomal Translocations ↔️ Philadelphia chromosome in CML

  Viral Insertion ↔️ HTLV-1 causing adult T-cell leukemia