AskDefine | Define mutagenic

Dictionary Definition

mutagenic adj : capable of inducing mutation (used mainly of extracellular factors such as X-rays or chemical pollution)

User Contributed Dictionary

English

Pronunciation

Adjective

mutagenic
  1. capable of causing mutation

Extensive Definition

In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the frequency of mutations above the natural background level. As many mutations cause cancer, mutagens are typically also carcinogens. Not all mutations are caused by mutagens: So-called "spontaneous mutations" occur due to errors in DNA replication, repair and recombination.

Effects of mutations

The changes in nucleic acid sequences by mutations include substitution of nucleotide base-pairs and insertions and deletions of one or more nucleotides in DNA sequences. Although many of these mutations are lethal, or cause serious disease, some have minor effects, as the changes they cause in the sequence of encoded proteins are not significant. Many mutations cause no visible effects at all, either because they occur in introns or because they do not change the amino-acid sequence, due to redundancy of codons.

Genetic drift

The change in a population’s genetic material due to the accumulation of random chance is called drift, and serves as a molecular clock. In general, the more nucleotide differences between two organisms, the more time has elapsed since their last common ancestor. Though it is difficult to determine in many organisms, estimates for mutation rates have been made for both E. coli and eukaryotes. It was estimated that, in these organisms, about one nucleotide in every 1010 is changed, and continues through reproduction to future generations of cells.

Discovery of mutagenesis

In the 1920s, Hermann Muller discovered that x-rays caused mutations in fruit flies. He went on to use x-rays to create Drosophila mutants that he used in his studies of genetics. He also discovered that x-rays not only mutate genes in fruit flies but also have effects on the genetic makeup of humans.

Nature of mutagens

Mutagens are usually chemical compounds or ionizing radiation. Mutagens can be divided into different categories according to their effect on DNA replication:
  • Some mutagens act as base analogs and get inserted into the DNA strand during replication in place of the substrates.
  • Some react with DNA and cause structural changes that lead to miscopying of the template strand when the DNA is replicated.
  • Some work indirectly by causing the cells to synthesize chemicals that have the direct mutagenic effect.
The Ames test is one method to determine how mutagenic an agent is.

Examples

Mutagens in fiction

In science fiction, mutagens are often represented as substances that are capable of completely changing the form of the recipient.
  • The Inhumans of Marvel Comics utilize a mutagen called the "Terrigen Mist."
  • The Teenage Mutant Ninja Turtles were supposedly created by means of mutagens, as well as their master Splinter and (in the 1987 cartoon) their enemies Bebop and Rocksteady.
  • In the Street Fighter movie, a bag of mutagens is used by General Bison to transform Carlos Blanka into a monster.
  • In Lego's Bionicle franchise, the water surrounding the pit is mutagenic, causing mutation in most of the major characters that enter the water.
  • The Metroid Prime trilogy is based around Phazon, a highly radioactive substance, which is characterized by its highly mutagenic and corruptive properties.
  • In Disney's Gargoyles, a mutagen is used to transform humans into mutates; a cross between gargoyles, humans, and electric eels.
  • In in 2007 film I Am Legend, a mutagen that was originally designed to cure cancer ends up wiping out 90% of the human race.
  • Tiberium, from the computer game series Command & Conquer, is a crystalline expanding mutagen that mutates all substances into Tiberium, and subsequently killing most living organisms.
  • In the PlayStation 3 game Resistance: Fall of Man, the invading Chimera, an alien race, infect humans with a mutagen to transform them into more Chimera.
  • In the Halo series the Flood parasite produces a powerful mutagen, turning its hosts into either a "combat form" or "carrier form" to propagate the race.

References

mutagenic in Czech: Mutagen
mutagenic in Danish: Mutagen
mutagenic in German: Mutagen
mutagenic in Estonian: Mutageen
mutagenic in Spanish: Mutágeno
mutagenic in French: Mutagène
mutagenic in Hebrew: מוטגן
mutagenic in Latvian: Mutagēns
mutagenic in Lithuanian: Mutagenas
mutagenic in Dutch: Mutageen
mutagenic in Japanese: 変異原
mutagenic in Polish: Mutagen
mutagenic in Portuguese: Agente mutagênico
mutagenic in Russian: Мутагены
mutagenic in Serbian: Мутаген
mutagenic in Finnish: Mutageeni
mutagenic in Swedish: Mutagen
mutagenic in Ukrainian: Мутаген
mutagenic in Urdu: مُطَفِّر
mutagenic in Chinese: 突變原
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