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Thread: radiation and cells

  1. #1 radiation and cells 
    Forum Freshman PA Ed's Avatar
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    Can someone explain, on the sub-atomic level, why radiation is harmful to us?

    Specifically, we are mostly made up of empty space. This is true for all matter ...
    The nucleus of the atom has a diameter of about meter, whereas the atomic diameter is about meter. This means that the nucleus has a diameter 10,000 times smaller than the atom. The great amount of empty space in an atom can be illustrated by the following analogy.

    Imagine the nucleus to be the size of a golf ball. Then on this scale the first electron shell would be about one kilometer from the golf ball, the second shell about four kilometers, the third nine kilometers and so on. If you find that hard to visualize then try this. The period at the end of this sentence, (depending on your monitor and the font you are using), is probably about 1/2 a millimeter in diameter. If that period represents the nucleus then the electrons in the first shell would be orbiting with a diameter about 50 meters around you.
    ... working with that, shouldn't most of the radiation pass right through us causing no ill effects?

    And, even if some radiation were to hit a neutron, proton or electron; why would that be harmful? What happens when an energized photon (a gamma particle) hits an electron or proton or neutron? What happens to that atom? How would it affect the actual cell that that atom is a part of? Same question for a beta particle (an electron). What would happen to the atom if one were to strike the nucleus or another electron?

    I know that radiation can mutate cells leading to cancer and even fry cells killing them. My question is: on the sub-stomic level (and working our way up), how does all of this happen?


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  3. #2  
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    First of all, you're right in that most radiation passed right through the atom. You can look at the experiments done by ernest rutherford with alpha sources and gold atoms where he worked out that most radiation passes right through but some still makes contact. This also explains why heavy metals are used as radiation shields, because they have smaller empty space to nucleus ratios so to speak, blocking more radiation.

    Radiation is in short the transfer of energy. When that energy gets passed to an atom (usually passing to its electrons) it causes those electrons to become 'excited' which basically means that the electrons move further away from the nucleus and start to move around. In this state they often break any bonds (particularly covalent bonds) they are involved in as they literally just get riped out of the the bond.

    That is in short how it damages our cells, because think of this. You have a strand of DNA, radiation hits it and causes the electrons around one of the nucleotides to become excited and it debonds from the DNA strand and floats away, the DNA rejoins but with one nucleotide missing. This causes a frameshift mutation, very serious. Another way I've heard of is a pair of single bond equivilents being broken and double bonds being formed, often between strands. These bonds are too powerful for enzymes to break down and effectively glue the DNA togeather which causes all sorts of problems.

    That was a really rough explination but I hope it answers your question.


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    http://web.princeton.edu/sites/ehs/o...htm#Mechanisms
    Injury to living tissue results from the transfer of energy to atoms and molecules in the cellular structure. Ionizing radiation causes atoms and molecules to become ionized or excited. These excitations and ionizations can:

    Produce free radicals.
    Break chemical bonds.
    Produce new chemical bonds and cross-linkage between macromolecules.
    Damage molecules that regulate vital cell processes (e.g. DNA, RNA, proteins).
    The cell can repair certain levels of cell damage. At low doses, such as that received every day from background radiation, cellular damage is rapidly repaired.
    At higher levels, cell death results. At extremely high doses, cells cannot be replaced quickly enough, and tissues fail to function.
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  5. #4  
    Forum Freshman PA Ed's Avatar
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    Quote Originally Posted by Chenzah
    First of all, you're right in that most radiation passed right through the atom. You can look at the experiments done by ernest rutherford with alpha sources and gold atoms where he worked out that most radiation passes right through but some still makes contact. This also explains why heavy metals are used as radiation shields, because they have smaller empty space to nucleus ratios so to speak, blocking more radiation.

    Radiation is in short the transfer of energy. When that energy gets passed to an atom (usually passing to its electrons) it causes those electrons to become 'excited' which basically means that the electrons move further away from the nucleus and start to move around. In this state they often break any bonds (particularly covalent bonds) they are involved in as they literally just get riped out of the the bond.

    That is in short how it damages our cells, because think of this. You have a strand of DNA, radiation hits it and causes the electrons around one of the nucleotides to become excited and it debonds from the DNA strand and floats away, the DNA rejoins but with one nucleotide missing. This causes a frameshift mutation, very serious. Another way I've heard of is a pair of single bond equivilents being broken and double bonds being formed, often between strands. These bonds are too powerful for enzymes to break down and effectively glue the DNA togeather which causes all sorts of problems.

    That was a really rough explination but I hope it answers your question.
    Thank you. That was very informative.
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    Glad I could help.
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