MadSci Network: Environment/Ecology |
Okay, Dustin,
Radiation is not a subject that I am too familiar with so I will
collaborate with our post-doctoral lab
person who knows more about it.
Essentially, when you are talking about ionizing radiation, you are
taking about radiation that occurs
below 380 nanometers (violet light) on the spectrum. This type of
radiation starts with Ultraviolet (UV),
then X-ray and down into Gamma rays. Basically what happens is that the
radiation breaks apart atomic
bonds in molecules which releases electrons and makes ions. That is why it
is called ionizing radiation.
Plants are better adapted to cope with naturally occurring ionizing
radiation, like UV, then people are
because they contain special chemical compounds that protect against UV
radiation. After all, they live in
the out of doors exposed to sunlight all the time, right? But people, on
the other hand, cannot cope with
this radiation nearly as well, hence the increasing awareness of skin
cancer. But, back to plants...
Molecules in living material (whether plant or animal) are complex and
large in size. Ionizing radiation
can cause changes in plants by breaking up these complex molecules. This
may change the structure of the
plant DNA, creating mutations or it might just kill the cell outright. The
loss of a few cells has little effect on
the growth of a plant. However, when massive amounts of cells are killed,
the plant may become stressed
and grow slower or even die. When DNA is mutated, the existing plant may
not show any mutations itself
but mutations may show up in its offspring. You cannot predict what
ionizing radiation will do to a
plant.
Mutations by radiation in plants can easily occur at certain stages.
Radiation can change the
reproducing portions of the parent plant causing mutations in its
offspring. However, in nature, this does
not occur often because pollen itself has an extremely tough exterior and
contains special pigments that
protect against naturally occurring radiation (UV). When people come
along, however, and use very high
concentrated doses of radiation, these protection mechanisms can be
overcome. The next stage where a
plant's DNA can be easily mutated is at the seed stage, before the plant
begins to grow. And finally, a very
young plant is more susceptible to radiation mutations than an older
plant.
The radiation may or may not kill the plant out right. Also, the plant
would not become "radioactive"
unless it was physically contaminated with the source of radiation. Think
about it this way. Fruits and
vegetables can be irradiated to kill insect pests, but it does not
contaminate the food. It is the same idea
what happens when you get an X-ray taken. You do not become radioactive
either.
I hope that this explains what you want to know. If not, you might want
to re-submit your question to
the physics category on MadSci Network.
Ted
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Scientist Network. Opinions
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