In recent decades, it seems as though the process of aging has slowly emerged as
an important field science.
With a great deal of literature and scientific work dedicated
solely to the subject of aging and its underlying causes, aging has become somewhat of a
Whether it is the human obsession with mortality or trying to maintain
one’s youthful appearance, aging is something experienced universally by all organisms,
Recent studies have tried to find many different explanations for aging
including research on free radicals, the role of different enzymes and molecules, DNA
damage, and DNA repair (Fisher, 1999).
To focus more closely on the topic, the role of
DNA damage and DNA repair in aging will be discussed.
A common but harmful thing occurs in our bodies almost every day; DNA
damage. As dangerous as this sounds most DNA damage goes unnoticed because of
processes in our cells that work to fix any damage caused.
Common causes of DNA
damage include spontaneous and gene-inherited mutations, which can occur during cell
reproduction (spontaneous) and during the formation of germ cells (gene-inherited)
(Gensler & Bernstein, 1981).
The formation of reactive oxygen species, also known as
free radicals, also can cause oxidative damage to DNA (Lombard
Ultraviolet radiation, X-rays, certain toxins, chemotherapy, and the harmful chemicals in
cigarette smoke and chewing tobacco have all been shown in studies to cause some sort
of damage to DNA.
As dangerous and harmful as these appear to be most of the damage
does become fixed and if it does not, many cells die.
In the case of gene-inherited
mutations in germ cells, if there is any severe genetic defect once the zygote has formed
that would inhibit normal cell function or normal function of the individual, the zygote
will terminate. If the cell is unable to repair the damaged DNA one of three different
states may occur: senescence, apoptosis, or unregulated cell division, which can cause the
growth of a tumor or the development of cancer (Lombard
Once damage has been inflicted upon DNA the cell begins a series of steps to
initialize the repair of DNA (Fisher, 1999).
DNA damage can be repaired by direct
Direct reversal fixes DNA damage by chemically reversing it.
reversal occurs when there is damage to the bases in DNA and not to the phospodiester
Ultraviolet radiation is a common cause of damage to DNA and is frequently
repaired using direct reversal to repair the damage caused by thymine dimers.