nov 18

What type of mutations contribute to cancer?

What type of mutations contribute to cancer?

Most cancer-causing mutations occur in somatic cells, but germline mutations can also play a role.

What is the relationship between cell-cycle regulation and cancer?

Cancer arises from malfunctions in the molecular signals, machinery, and checkpoints that regulate cell division.

What are key molecules involved in the cell cycle?

Cyclins and Cyclin-Dependent Kinases (Cdks) are key molecules, with cyclin levels fluctuating during the cycle while Cdks remain constant.

What is the difference between familial and sporadic cancers?

Familial cancers are inherited and run in families, while sporadic cancers are not inherited.

What are proto-oncogenes?

Proto-oncogenes normally stimulate cell proliferation but can mutate into oncogenes, leading to uncontrolled cell growth.

What are oncogenes?

Oncogenes are mutant proto-oncogenes with dominant, gain-of-function mutations that promote cancer cell transformation.

What are tumor suppressor genes?

Tumor suppressor genes normally inhibit cell proliferation, and loss-of-function mutations in these genes can lead to cancer.

What are mutator genes?

Mutator genes are typically recessive, loss-of-function mutations that increase mutation rates and contribute to cancer development.

What is Chronic Myelogenous Leukemia (CML)?

CML is caused by translocations leading to a cancerous state in white blood cells.

How does telomerase relate to cancer?

Mutations that reactivate telomerase provide a survival advantage to cancer cells by preventing chromosome shortening.

What role do viruses play in cancer?

Viruses can induce cancer by disrupting normal cell cycle controls or inserting oncogenes into the host genome.

What is the Rous Sarcoma Virus (RSV)?

RSV is a retrovirus that contains the src oncogene, which produces uncontrolled growth by constitutively activating a tyrosine kinase.

How do retroviruses cause cancer?

Retroviruses can integrate their genome into the host DNA, disrupting cell cycle regulation and promoting uncontrolled cell growth.

What is the role of DNA tumor viruses in cancer?

DNA tumor viruses typically induce DNA replication but may rarely transform cells by integrating their DNA into the host genome.

What is the Ras protein?

Ras is a G-protein involved in cell signaling that activates transcription of cell-cycle-specific genes when mutated, leading to cancer.

What is the function of tumor suppressor genes?

Tumor suppressor genes suppress uncontrolled cell proliferation and mutations in these genes can lead to cancer.

What is the RB gene?

The RB (retinoblastoma) gene is a tumor suppressor gene involved in preventing eye tumors, particularly in childhood retinoblastoma.

What is the two-hit hypothesis for retinoblastoma?

This model suggests that two mutations are required to inactivate both copies of the RB gene, leading to tumor development.

What is the difference between hereditary and sporadic retinoblastoma?

Hereditary retinoblastoma involves one inherited and one somatic mutation, while sporadic cases involve two somatic mutations.

What are cyclins?

Cyclins are proteins that regulate the cell cycle by activating Cdks, with their levels fluctuating during the cycle.

What is the significance of the src oncogene?

The src gene, the first oncogene discovered, codes for a tyrosine kinase involved in cell growth and is constitutively active in some cancers.

What are gain-of-function mutations?

Gain-of-function mutations in genes like proto-oncogenes increase their activity, leading to cancer.

What are loss-of-function mutations?

Loss-of-function mutations in tumor suppressor genes disable their ability to inhibit cell proliferation, contributing to cancer.

What is telomere shortening?

Telomere shortening occurs in dividing cells and can lead to chromosomal instability and cancer if telomerase is reactivated.

What are RNA tumor viruses?

RNA tumor viruses, such as retroviruses, cause cancer by carrying oncogenes originally derived from the host genome.

What are DNA tumor viruses?

DNA tumor viruses typically do not carry oncogenes but may induce cell proliferation by integrating their DNA into the host genome.

What is Knudson’s two-hit hypothesis?

Knudson proposed that two mutations are needed to cause hereditary cancers like retinoblastoma, one inherited and one somatic.

What is the function of Cdks?

Cdks (Cyclin-Dependent Kinases) regulate the cell cycle and must bind to cyclins to become active.

What are papilloma viruses?

Papilloma viruses are DNA tumor viruses linked to cancers such as cervical cancer by disrupting cell cycle regulation.

How does telomerase activation affect cancer cells?

Telomerase activation allows cancer cells to avoid senescence and continue dividing indefinitely.

What is the role of checkpoint proteins in the cell cycle?

Checkpoint proteins ensure proper cell cycle progression, preventing division if errors are detected.

What is the G0 phase?

The G0 phase is a resting stage where cells exit the cycle and do not divide until reactivated.

What is the relationship between mutations and cancer?

Cancer arises from multiple mutations in proto-oncogenes, tumor suppressor genes, and mutator genes.

What is the significance of the G1 checkpoint?

The G1 checkpoint ensures cells are ready for DNA synthesis by checking for DNA damage and nutrient availability.

What is the difference between DNA repair genes and mutator genes?

DNA repair genes fix errors during replication, while mutator genes, when mutated, lead to increased mutation rates.

What is clonal expansion in tumors?

Clonal expansion is the process by which a single mutated cell divides and forms a tumor with identical genetic mutations.

What is the function of p53?

p53 is a tumor suppressor gene that induces cell cycle arrest or apoptosis in response to DNA damage.

What is the role of apoptosis in cancer prevention?

Apoptosis eliminates damaged or potentially cancerous cells, preventing tumor formation.

What is the difference between benign and malignant tumors?

Benign tumors do not invade surrounding tissues, while malignant tumors are invasive and can metastasize.

What is metastasis?

Metastasis is the spread of cancer cells from the primary tumor to distant sites in the body.