Molecular Causes of Cancer

Question 1

What are proto-oncogenes?

Answer 1

A gene that codes for positive regulators —> stimulate cell growth, inhibit differentiation, and halt cell death

Question 2

What are oncogenes?

Answer 2

A mutated form of proto-oncogenes which produce excessive amounts of positive regulators

Question 3

What are tumor suppressor genes?

Answer 3

Genes that code for negative regulators halting cell cycle progression and fix DNA damage

Question 4

How do genetic mutations lead to cancer?

Answer 4

Multiple mutations leading to prolonged and accumulated cell damage leads to cancer

Question 5

Why is cancer considered to be a disease of the cell cycle?

Answer 5

Cancer is the uncontrolled cell growth and replication that bypass checkpoints in cell cycle developing causing mutations

Question 6

What types of mutations turn proto-oncogenes into oncogenes?

Answer 6

Point mutation: overactive protein (overproduction if in promoter region)
Gene duplication: twice as many positive regulators as needed

Question 7

What is the promoter region of a gene? How do mutations in this region affect protein production?

Answer 7

Part of gene starting transcription - if mutated results in increased or decreased in protein production

Question 8

List examples of proto-oncogenes and tumor suppressor genes and what they do

Answer 8

Proto-oncogene: HER 2 - receives signals for cell growth
Tumor suppressor: BRCA 1/2 - Repair DNA damage