All genes are susceptible to mutations. But each gene has its own rate of mutability, so it is more or less subject to change. Some environmental influences can increase the percentage of gene mutations in chromosome. A science that examines all types of gene-toxic agents and determines what causes mutations in the human genome is called genotoxicology. All factors that can cause hereditary changes materials are mutagenic. A mutagen in genetics is any physical, chemical and biological agent that alters genetic material either way. Mutagenic factors usually act on the DNA molecule of an organism and thus increase it frequency of mutations above natural levels. Just as many mutations can cause cancer, so can mutagens they can also be carcinogenic. Not all mutations are caused by mutagens - spontaneous mutations occur due to random hydrolysis, error in DNA replication and recombination.
Discovery of mutagens
The first mutagens identified were carcinogens, substances that were shown to be associated with cancer. Tumors were described more than 2,000 years before the discovery of chromosomes and DNA. 500bc Greek doctor Hippocrates called cancer-like tumors "karkinos", which means cancers. In 1567 a Swiss physician Paracelsus suggested that unidentified substances in mined ores (radon, gas) caused diseases in miners. In England in 1761, John Hill was the first to directly link the connection between chemicals and cancer, noting that tobacco consumption can cause cancer. It's Edgar Altenburg that demonstrated the mutagenic effect of UV radiation.
Hermann Joseph Muller conducted three experiments in 1926 and 1927 which showed that x-rays, a form of high-energy radiation, can cause genetic mutations and changes in genome of the organism, especially in ova and sperm In his experiments, Muller exposed fruit flies (Drosophila) to X-rays. In 1927, Muller described the results of his experiments in "Artificial Gene Transmutation" and "The Problem of Gene Modification." It's his discovery that indicated the causes of the mutation and for that research he was later awarded the Nobel Prize for physiology and medicine in 1946. Muller’s X-ray experiments found that x-rays mutated genes and that eggs and sperm are particularly sensitive to such genetic mutations.
Mutagenic effects
Mutagenic factors have the greatest impact on the DNA molecule. The action of mutagens leads to loss of gene functions. Strong mutagens can lead to instability on the chromosome, its breakdown, structure changes in the form of deletion, inversion and translocation.
Deletion is a type of structural change on a chromosome, it is the loss of a part of a chromosome.
The reversal of a gene sequence in a chromosome is called a inversion, it occurs after the breakage of a chromosome in two places, and rotating that broken part by 180 degrees.
Translocation is the transfer of part of one chromosome to an inhomogeneous chromosome
Types of mutagens
We classify mutagens into three groups: physical, chemical and biological:
Do you chew gum and drink coffee? Caffeine causes mutations in the c-K race oncogene. It is a gene discovered in mutated form in pancreatic cancer. Unlike coffee, chewing gum contains more chemicals - mutagenic and carcinogenic - at least three and usually more. Aspartame, BHT (butyl-hydroxy-toluene), titanium dioxide, rubber base, lanolin and a whole range other additives produced from modified raw materials suc as E965.
Aspartame is an artificial sweetener. It consists of three chemicals, and is found in "sugar-free" products. It releases toxins into the body (methanol and formaldehyde) retained in the liver. They are associated with anomalies in children, brain tumors and weight gain.
BHT is banned in most countries of the world because it is very poisonous. However, it is used in small quantities as a preservative in chewing gum. It is associated with kidney and liver poisoning, hyperactivity in children. It is also carcinogenic.
Titanium dioxide is found in gums for teeth bleeching. It has been linked to autoimmune disorders, asthma and Crohn’s disease. It's potentialy carcinogenic.
The rubber base of chewing gum is a secret since its composition is generally not published. Experts say it is a mixture of elastomers, resins and plasticizers, but do not point out the presence of petroleum paraffin derivatives, carpentry glue - polyvinyl acetate. All these substances are associated with different forms cancer.
Read more on how these affect your health, by clicking the link:
Chemical mutagens: food additives, pesticides, pharmaceutical drugs etc.
Physical mutagens: Radiation from scanners, x rays etc.
Heat: UV rays, radio waves etc.
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