I have a very intelligent friend who is a light smoker, and also a Biology layperson.
I wondered whether understanding exactly how cigarettes smoke can cause cancer, might encourage him to smoke less (or quit entirely).

So how would you explain to a Biology layperson how cigarettes smoke might cause cancer?

To clarify, I am looking for a detailed explanation for a layperson, that makes the cause-and-effect much more vivid for them, and thus makes it much more likely that the intelligent layperson would internalize the risks of smoking.

Online resources that I found either gave a too simple answer or concentrated on statistics (which are usually hard for humans to internalize, if I understand correctly).
(Nothing wrong with such explanations, they are just not what I am looking for.)

  • 1
    $\begingroup$ I'm voting to close this question as off-topic because it is a request for proof-reading a document, rather than for an answer to a biological problem, which is what is appropriate to SE Biology. It might possibly be re-phrased as "How does smoking cause cancer?" with the bulk of the question being moved to an answer from the poster (which is allowed). $\endgroup$
    – David
    Jun 17 '19 at 22:32
  • $\begingroup$ @David Is a solution for a biological problem in layman terms appropriate for biology.SE? anyway, I edited according to your suggestion (hopefully). Thanks :) $\endgroup$ Jun 18 '19 at 5:39
  • $\begingroup$ @David By the way, I wrote the question after I had already sent my friend my explanation (which wasn't even in English). I just thought that surely many biology.SE users could explain it better than me, and so I posted the question (which included my attempt at explaining it, as I thought that biology.SE requires showing your efforts in the question). $\endgroup$ Jun 18 '19 at 6:01
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    $\begingroup$ There are tons of resources on this, especially for laymen. Did you even try looking at them? Simple answer to your question is that cigarette smoke contains many harmful substances and some of them are carcinogens. Regarding your original question: you start with DNA replication and how a particular carcinogen can cause mutations in DNA. That is a very broad background and is actually counter-productive. In your current form, I might say that your question is broad and also not useful as there are loads of resources on this topic from reputed organizations, for laypersons. $\endgroup$
    Jun 18 '19 at 8:27
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    $\begingroup$ @OrenMilman If they go into details then laypersons won't understand. If one wants to understand how mutations happen in DNA then they have to look at other sources. Stackexchange format is definitely not suitable for answers like these: starting from DNA composition to the effect of carcinogens. There are too many processes involved and one can learn a lot about any of those processes. If you want to educate people then you can try writing a blog. $\endgroup$
    Jun 18 '19 at 9:15

I encountered the following paragraph in the textbook Life: The Science of Biology:

Some chemicals add groups to the bases. For instance, benzopyrene, a component of cigarette smoke, adds a large chemical group to guanine, making it unavailable for base pairing. When DNA polymerase reaches such a modified guanine, it inserts any one of the four bases at random. Three-fourths of the time the inserted base is not cytosine, and a mutation results.

After finding the following quote in Wikipedia's Benzo(a)pyrene page, I decided to explain specifically how BaP can cause cancer:

BaP has since been identified as a prime carcinogen in cigarette smoke.

My explanation:

  • A protein molecule is a chain of amino acids. Proteins are hugely important, as they are responsible for most of the cellular functions.
  • A DNA molecule is a chain of nucleic acids. There are 4 types of nucleic acids in DNA: A,G,C,T.
  • Having intact DNA molecules is crucial, because they include the encoding of proteins, according to which cells synthesize proteins.
  • A mutation is an alteration of a DNA molecule.
  • A mutation might lead to our cells synthesizing a malfunctioning protein. If a protein that should regulate cell division is malfunctioning, then the result might be uncontrolled cell division - cancer.
  • When you smoke, the chemical BaP (which is found in cigarettes smoke) might alter a G nucleic acid in a DNA molecule in some cell in your body. Later, when this cell tries to divide, it makes a copy of each of its DNA molecules, but it won't be able to identify that G nucleic acid (that BaP altered), so it would put a random nucleic acid in the copied DNA molecule. Thus, there is a 3/4 chance for a mutation.

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