Cancer Biology and Mechanisms

These flashcards cover key concepts from the lecture on cancer biology, including definitions, mechanisms, and the roles of various genes.

What defines a cancerous cell?

A cell becomes cancerous when it undergoes mutations or abnormally expressed genes leading to loss of cell cycle control.

What are the three main cell cycle checkpoints?

G1/S checkpoint, G2/M checkpoint, and M checkpoint.

What is the role of the G1/S checkpoint?

It monitors cell size and DNA integrity, determining if the cell can proceed to division.

What happens at the G2/M checkpoint?

It checks for DNA synthesis and damage before the cell enters mitosis.

What is apoptosis?

Apoptosis is programmed cell death that occurs when a cell's DNA or damage is too severe to repair.

What are proto-oncogenes?

Genes whose products promote cell growth and division when needed.

What is an oncogene?

A mutated proto-oncogene that has a gain-of-function phenotype leading to uncontrolled cell growth.

What is the function of tumor suppressor genes?

They regulate cell-cycle checkpoints and initiate the process of apoptosis.

What is the most frequently mutated tumor-suppressor gene?

p53, which is mutated in approximately 50% of all cancers.

How do mutated tumor-suppressor genes affect the cell cycle?

They exhibit a loss-of-function phenotype, making them unable to respond to cell-cycle checkpoints or undergo apoptosis.

What is the significance of Ras in cancer biology?

Ras is a proto-oncogene that, when mutated, becomes an oncogene continuously activating cell growth and division signals.

What role do epigenetic changes play in cancer?

They can alter gene expression by affecting DNA methylation and histone acetylation, impacting tumor suppressor and proto-oncogene functions.

Define benign tumors.

Benign tumors are masses of the same type of cells in one area that do not invade surrounding tissues.

Define malignant tumors.

Malignant tumors are dangerous tumors that invade and destroy surrounding normal cells.