Genome Regulation: Cancer and Cell Cycle Control

Study Notes

Cancer and Gene Regulation

Cancer results from genetic changes that affect cell cycle control, involving the same gene regulation systems active during embryonic development.

Types of Genes Associated with Cancer

Cancer can be caused by mutations in genes regulating cell growth and division.
Tumor viruses can cause cancer in animals, including humans.
Oncogenes are cancer-causing genes, while proto-oncogenes are their normal cellular counterparts responsible for normal cell growth and division.
Conversion of a proto-oncogene to an oncogene can lead to abnormal stimulation of the cell cycle.

Proto-oncogene Conversion to Oncogenes

Proto-oncogenes can be converted to oncogenes through:
- Movement of DNA within the genome, resulting in increased transcription near an active promoter.
- Amplification of a proto-oncogene, increasing the number of gene copies.
- Point mutations in the proto-oncogene or its control elements, causing increased gene expression.

Tumor-Suppressor Genes

Tumor-suppressor genes help prevent uncontrolled cell growth.
Mutations decreasing protein products of tumor-suppressor genes may contribute to cancer onset.
Tumor-suppressor proteins:
- Repair damaged DNA.
- Control cell adhesion.
- Inhibit the cell cycle in the cell-signaling pathway.

Interference with Normal Cell-Signaling Pathways

Mutations in the ras proto-oncogene and p53 tumor-suppressor gene are common in human cancers.
Ras gene mutations can lead to production of a hyperactive Ras protein, increasing cell division.
Suppression of the cell cycle is critical in cases of DNA damage; p53 prevents a cell from passing on mutations.

Description

This quiz covers the relationship between cancer and genetic changes affecting cell cycle control, including the role of gene regulation systems in embryonic development and cancer. Understand the types of genes associated with cancer.