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Apelacio, Lorina Lynne C. Prof. Norma Soliman

BSN301 Geriatric Nursing

Somatic Mutation Theory

This was developed by Thomas Szilard.This theory holds that Mutations are those inheritable changes that occur in the cellular

DNA. If there is extensive damage to DNA and it is not repaired, then there will probably be

an alteration in a genetic sequence.

Somatic mutation theory argues that genetic damage, originally suggested to arise frombackground radiation, causes senescence (aging). (Handbook of Theories of Aging by K.

Warner Schaie, PhD, Vern L. Bengtson, PhD)

Exposure to ionizing radiation causes genetic damage and shortens life span. It states thatgenetic damage or mutations are radiation induced. The resulting mutations will accumulate,

ultimately leading to functional failure and death (Cristofalo, 1990) (Geriatric audiology by

Barbara E. Weinstein)

Somatic mutation refers to genetic mutation, in other words, that genes somehow split, orthey are copied incorrectly, and cannot function properly. This causes more exposure to

toxins, radiation, and ultraviolet light. The molecules become damaged.

The simple idea behind this theory is that with the tens of thousands of genes that arereproduced every time a cell in your body divides to make a new cell, an occasional error

happens. Most of these incorrectly copied genes never create any problems. However,

without being repaired, later copies make the problem worse. Eventually, the line of cells

coming from the errant copy no longer quite function like the original cell. This process

happens over and over again during a span of several decades until enough poorly

functioning cells are present to cause changes in the tissue that they comprise.The somatic mutation theory states that random changes to the DNA of your cells can cause

your cells, and eventually your body, to stop functioning correctly. Throughout your life

time, your body is constantly creating new cells. Every time one of your cells divides to

create two new cells, there is a possibility that the DNA from the first cell will be copied

incorrectly. This results in a mutation, a change in the copy of your DNA contained by the

new cells. This mutation may be caught and corrected, but some mutations will be missed

and some of these mutations will affect the way the new cell functions.

According to this theory genetic mutations occur and accumulate with increasing age,causing cells to deteriorate and malfunction.

What does Mutation mean?

Mutation is the new cell which is different from its parent cell. However, in most of themutations, there is a deteriorating trend in its organisms indicating that the copy of the cell

when it mutates is not good or same as the original. Mutation ultimately results in the bodys

aging process.

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These are changes in a cell=s DNA, which are passed on to daughter cells during mitosis.Since genes on DNA code for specific proteins, mutated genes may produce defective

proteins, which do not work properly.

Certain chemicals and radiation cause mutations to occur in DNA by giving off high energyparticles. These particles collide with the DNA and knock off atoms of the DNA randomly,

damaging it. DNA consists of sequences of four possible nitrogenous bases: adenine,

guanine, cytosine, and thymine, paired so that adenine always pairs with thymine, and

guanine always pairs with cytosine. As cells repair the damaged DNA, a different DNA base

is often substituted. This base-substitution is known as a point mutation and can cause the

production of a defective or damaged protein.

Apart from being caused by radiation or chemicals, mutations also occur spontaneously butat lower rates. Physicist Leo Szilard and biochemist Denham Harmon proposed that because

most mutations are harmful, the more spontaneous mutations that arise, the more

abnormalities that arise as defective proteins are produced. These could ultimately kill an

individual (Ricklefs and Finch, 1995, 20). It has been proven that DNA is chemically alteredduring aging. It is unclear how changes such as these arise, but similar changes seem to be

caused by exposure to mutation-causing chemicals, some of which are found in tobacco

smoke (Ricklefs and Finch, 1995, 21).