16 Questions
What are the three classes of carcinogenic agents?
Chemicals, radiant energy, microbial agents
What are the two stages of chemical carcinogenesis?
Initiation and Promotion
What is the difference between direct-acting and indirect-acting agents?
Direct-acting agents require no metabolic conversion to become carcinogenic, while indirect-acting agents require metabolic conversion to an ultimate carcinogen before becoming active.
What are examples of indirect-acting agents?
Polycyclic hydrocarbons, aromatic amines, azo dyes
What is the main cause of carcinogenesis according to the text?
Genetic damage
What is the multistep nature of carcinogenesis attributed to?
Involvement of several oncogenes and tumor suppressor genes
What is the primary target for chemical carcinogens?
DNA
What type of radiation is derived from sunlight and has the ability to damage DNA by forming pyrimidine dimers?
UV rays
What is the essential first step in the process of initiation in carcinogenesis?
Unrepairable and non-lethal DNA damage
What type of UV is carcinogenic?
UV-B
What is the mechanism by which UV rays damage DNA?
Formation of pyrimidine dimers in the DNA
What provides the best evidence for the increased risk of skin cancer in sun-exposed parts of the body?
Increased risk of skin cancer in patients with xeroderma pigmentosum
What is the role of initiators in the process of carcinogenesis?
Cause permanent DNA damage (mutation)
What is the effect of exposure to promoters on initiated cells?
Proliferation and clonal expansion
What is the primary effect of most chemical carcinogens?
Mutagenic
What is the mechanism by which ionizing radiation can lead to carcinogenesis?
Highly reactive electrophiles interacting with electron-rich sites in the cell
Test your knowledge of the causes of cancer, including the steps of carcinogenesis, carcinogenic agents, and the effects of tumors on the host. Explore the genetic damage at the heart of carcinogenesis and the three classes of carcinogenic agents: chemicals, radiant energy, and microbial agents.
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