Retinoblastoma and Tumor Suppressor Genes

The video explains tumor suppressor genes, which regulate the cell cycle and prevent cancer. It covers categories of tumor suppressor proteins, such as DNA repair proteins and cell cycle repressors. The Two-Hit Hypothesis is discussed, highlighting the need for mutations in both alleles to manifest effects. The Retinoblastoma protein's role in halting cell cycle progression is detailed, along with the p53 protein's critical functions in DNA repair and apoptosis. The concept of Dominant Negative mutations in p53 is also introduced.

What is the primary function of tumor suppressor genes?

• To accelerate cell division

• To repair damaged DNA

• To halt the cell cycle and promote apoptosis

• To enhance protein synthesis

Which category of tumor suppressor proteins is responsible for recognizing and repairing DNA damage?

• Cell cycle repressors

• DNA repair proteins

• Transcription factors

• Apoptosis initiators

According to the Two-Hit Hypothesis, what is required for a tumor suppressor gene to manifest its effect?

• Only one allele must be mutated

• Both alleles must be mutated

• The gene must be overexpressed

• The gene must be silenced

What is the role of the Retinoblastoma protein in the cell cycle?

• It enhances transcription of S phase promoting factors

• It promotes apoptosis in healthy cells

• It prevents the cell from entering the S phase when DNA is damaged

• It accelerates the transition from G1 to S phase

How does the Retinoblastoma protein inhibit cell cycle progression?

• By binding and inhibiting transcription factors

• By degrading histone proteins

• By activating cyclin-CDK complexes

• By promoting DNA synthesis

What percentage of colon cancers involve the loss of the p53 protein?

• 65%

• 50%

• 30%

• 80%

What is the function of the p53 protein when DNA damage is detected?

• It promotes cell division

• It activates DNA repair proteins

• It enhances protein synthesis

• It degrades damaged DNA

What is the role of p21 in the cell cycle?

• It enhances protein synthesis

• It binds to cyclin-CDK complexes to halt the cell cycle

• It promotes the transition from G1 to S phase

• It degrades damaged DNA

What is a 'Dominant Negative' mutation in the context of p53?

• A mutation that increases DNA repair

• A mutation that silences the p53 gene

• A mutation that prevents the normal allele from functioning

• A mutation that enhances p53 function

Which of the following is an exception to the Two-Hit Hypothesis?

• Mutations in the p53 gene product

• Mutations in DNA repair proteins

• Mutations in cell cycle repressors

• Mutations in apoptosis initiators