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Deeltoets 3 (Zie essential cell biology) - hfts

Q: The difference between mutagenic and non-mutagenic carcinogens

Mutagenic carcinogens interfere with DNA. Base pair substitutions, frame shift. Non-mutagenic carcinogens are involved in stimulating the tumour promotion. Tumour promoting substances stimulate cell proliferation and inhibit cell differentiation and apoptosis. Unlike mutagenic compounds, tumour promoting compounds do not interfere directly with DNA and their effect is reversible. Many endogenous substances (e.g. hormones) may act as tumour promoting agents.

Q: Three different phases in cancer development & how compounds can stimulate the corresponding processes in these phases

1. The initiation phase: DNA is permanently changed, daughter cells differ from parental cells 2. Promotion phase: Cell loses its differentiation and gains new characteristics --> proliferation 3. Progression phase : Tumour invades surrounding tissue Chemical carcinogenesis means that a chemical substance is capable of stimulating one or more of these phases. Carcinogenic compounds are often named after the phase that they affect, i.e. initiators (also called mutagens), tumour promotors, and tumour progressors.

4 important questions on Deeltoets 3 (Zie essential cell biology) - hfts

Why only error in nucleotide order during DNA replication?

It should be realized that a DNA adduct can only cause an error in the order of nucleotides (i.e. a mutation) if it is present during DNA replication. Before a cell goes into the DNA synthesis phase of the cell cycle, however, the DNA is thoroughly checked, and possible errors are repaired by DNA repair systems.

The difference between mutagenic and non-mutagenic carcinogens

Mutagenic carcinogens interfere with DNA. Base pair substitutions, frame shift.
Non-mutagenic carcinogens are involved in stimulating the tumour promotion. Tumour promoting substances stimulate cell proliferation and inhibit cell differentiation and apoptosis. Unlike mutagenic compounds, tumour promoting compounds do not interfere directly with DNA and their effect is reversible. Many endogenous substances (e.g. hormones) may act as tumour promoting agents.

Chemicals and cancer: Percival Pott

Percival Pott was the first person:
-to link cancer development to chemical substances
-to link early exposure to later cancer development (The delay in cancer development after the early childhood exposure can be attributed to the absence of a tumour promotor. Only after the chimney sweepers had gone through puberty they had sufficient testosterone levels, which stimulates scrotum tissue growth and in this case acted as an endogenous tumour promoting agent)
-to obtain better occupational health by decreased exposure through better hygiene.

Three different phases in cancer development
& how compounds can stimulate the corresponding processes in these phases

1. The initiation phase: DNA is permanently changed, daughter cells differ from parental cells
2. Promotion phase: Cell loses its differentiation and gains new characteristics --> proliferation
3. Progression phase: Tumour invades surrounding tissue

Chemical carcinogenesis means that a chemical substance is capable of stimulating one or more of these phases. Carcinogenic compounds are often named after the phase that they affect, i.e. initiators (also called mutagens), tumour promotors, and tumour progressors.

The question on the page originate from the summary of the following study material:

immunologie en celbiologie

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