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>> Changes in DNA, some of which are inherited, others of which were due
to outside causes can lead to cancer.
The cancer process begins when a cell starts to divide.
In division the DNA begins to unwind in a strand of what's called messenger RNA begins
to copy one of the DNA strands, if copying process goes wrong, cancer can occur.
>> Instead of fully copying a DNA strand the copier strand cannot copy bases
that are missing on the DNA.
What results is called an oncogene which is a mutated gene
which may have missing base pairs or other abnormalities.
The oncogene is then processed by something called a ribosome,
shown here as a large blue structure.
The resulting protein will have abnormalities depicted here
as transparent globes which can lead to cancer.
During the copying process a free radical spun off perhaps
by ionizing radiation strikes the DNA and causes an incorrect pairing of two bases.
Had the error not occurred in this particular tumor suppressor gene,
cancer might have been averted because this particular gene helps turn off the
cancer process.
A mismatch of base pairs shown here as a green base pairing with a purple base instead
of a proper yellow purple pairing can occur during the DNA copying process.
A mismatch repair gene then might signal a protein to help repair the process.
But before the repair process can be completed an outside agent
such as the chemical benzine interferes and defeats the repair leading to a cancerous cell.
>> In all three of our examples something went wrong, the DNA lead to a mutated RNA copy
and formation of new mutated or cancerous cells arose.
Cancer cells divide at a much quicker rate
than normal cells forming irregularly sized cells with enlarged nuclei.
As cancer cells continue to divide they form masses called tumors.
Tumors can sometimes be treated with new molecular agents
such as the breast cancer drug, Herceptin.
This drug can be injected into a patient, try and repair the DNA copying process that got
out of control, destroy the tumor so that only normal cells remain
and future cell division only originates from normal unmutated DNA.