Lecture 3 - The Nature of Cancer [Population Dynamic & History in Research] Flashcards
In reference to population dynamics, what is cancer dependent on? Give 4 main factors.
1 - Population, ethnicity
2 - Country, region, or other environmental factors
3 - Lifestyle
4 - Gender
Give conclusive proof that cancer can result from environmental causes (in reference to countries)
In Japan, dietary/environmental conditions are favourable to stomach cancer. In Hawaii, due to these same conditions, prostate cancer is a favoured contender. Japanese immigrants who moved to Hawaii were found to have increased rates of prostate cancer and decreased rates of stomach cancer. In essence, due to the environmental conditions, they adopted the health risks as well. Cool.
Give a brief history of cancer research. Include 4 scientists, their discoveries, and a sentence related to mustard gas.
1 - Boveri: experimented with sea urchin embryos and discovered that chromosomal dysfunction can lead to increased proliferation.
2 - Yamagiwa: induced carcinomas on a predictable schedule by coating rabbits’ ears with coal tar. First to explore the theory surrounding carcinogens
3 - Rous: experimented with transplantation of tumors from one chicken into another. Used a filter to prevent cells from transferring and only used fluid. Determined that viruses can cause cancer [since no cells transferred]
4 - Muller: discovered one could use radiation to induce mutations in the genome of fruit flies.
Mustard gas is carcinogenic due to the alkylating agents it contains
What is “The Ames Test”. Describe it.
The Ames test is a test in which the mutagenicity of a chemical is tested [for safety purposes].
An auxotrophic [Histidine dependent] strain of salmonella is used. Rat liver extract is added to simulate metabolic effects and the test chemical is also mixed in. The bacteria is then plated on agar plates lacking the histidine nutrient. If many cultures grow, mutation has occurred to allow reproductive success in the absence of histidine. If few cultures have grown, there was a lower mutagenic effect meaning the chemical is safer… in a manner of speaking
What is the difference between a carcinogen and a mutagen? What are some of the different types of mutations?
A mutagen causes a mutation that may or may not be detrimental to the overall organism. A carcinogen causes cancer. Mutations can be silent (no effect), negative (bad), or positive (good). Mutations can include…
Missense mutation: codon altered, altered AA produced
Nonsense mutation: codon coded for “STOP” premature abortion of transcription
Silent mutation: codon altered but still codes for same AA
How?
Substitution/Point: one base swapped for another
Insertion: inserts base(s)
Deletion: removeds base(s)
Frameshift: alters reading bath of transcription enzyme
What are three other methods of testing mutagenicity and carcinogenicity [Other than the Ames Test]?
1 - Sister Chromatid Exchange [SCE]
2 - Specific gene loss [HGPRT enzymes]
3 - Chromosomal aberrations [Karyotyping]
Are all the tests for carcinogens and mutagens perfect? Give some examples (3).
No, they are imperfect as testing for long term effects is difficult [humans live long lives, each generation is the guinea pig for the one succeeding it]. Examples of failures: 1 - Agent Orange 2 - Asbestos 3 - Tobacco Smoke
