DNA Repair, Fact vs Fiction

By | December 7, 2008

This morning I found an interesting exchange between a rationalist and a spiritualist regarding DNA repair claims. This lead me to Wikipedia, which has a nice rational summary of DNA repair:

DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and Radiation can cause DNA damage, resulting in as many as 1 million individual molecular lesions per cell per day.[1] Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell’s ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell’s genome, which affect the survival of its daughter cells after it undergoes mitosis. Consequently, the DNA repair process is constantly active as it responds to damage in the DNA structure.

DNA damage, as distinct from mutation, is a primary cause of aging.  Contrary to popular belief, experimental evidence has failed to show that mutation cause aging.

What is the difference between DNA damage and DNA mutation?

Damage is a physical abnormality in DNA. It can be detected by enzymes and repaired.  Most commonly, one side of the double helix DNA strand is damaged (see illustration, right), but double strand breaks also happen and can be repaired.

Ad DNA mutation is a change in the base sequence of the DNA. In other words, both sides of the DNA strand changes. A mutation cannot be recognized by enzymes once the base change is present in both DNA strands.  Mutations cannot be repaired.

At the cellular level, mutations can cause alterations in protein function and regulation. Mutations are replicated when the cell replicates. In a population of cells, mutant cells will increase or decrease in frequency according to the effects of the mutation on the ability of the cell to survive and reproduce. Although distinctly different from each other, DNA damages and mutations are related because DNA damages often cause errors of DNA synthesis during replication or repair and these errors are a major source of mutation. – wiki

The rate of normal DNA repair in your healthy cells is amazing.

In humans, DNA damages occur frequently and enzyme mediated DNA repair processes have evolved to cope with them. On average, about 800 DNA damages occur per hour in each cell, or about 19,200 per cell per day (Vilenchik & Knudson 2000). – wiki

The rate of DNA repair is dependent on many factors, including the cell type, the age of the cell, and the extracellular environment. A cell that has accumulated a large amount of DNA damage, or one that no longer effectively repairs damage incurred to its DNA, can enter one of three possible states:

  1. an irreversible state of dormancy, known as senescence
  2. cell suicide, also known as apoptosis or programmed cell death
  3. unregulated cell division, which can lead to the formation of a tumor that is cancerous

The DNA repair ability of a cell is vital to the integrity of its genome and thus to its normal functioning and that of the organism. Many genes that were initially shown to influence lifespan have turned out to be involved in DNA damage repair and protection.[2] Failure to correct molecular lesions in cells that form gametes can introduce mutations into the genomes of the offspring and thus influence the rate of evolution. …

Can our thoughts influence the rate of DNA repair? I don’t know about that, but our thoughts can influence our actions, and our actions can cause us to eat right, exercise, get enough sleep, to seek clean fresh air and water and to find comfort in our relationships.

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