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Spontaneous Mutations
Spontaneous Mutations
One example of spontaneous mutation is the appearance of sickle cell anemia in humans. People with Sickle cell anemia endure severe symptoms, including pain and anemia. The disease is caused by a mutated version of the allele that helps make hemoglobin. Hemoglobin is a protein that carries oxygen in red blood cells. People with two recessive alleles for the sickle cell gene have the disease. It occurs naturally, and it has stuck around for new generations because it is beneficial to carry the sickle cell anemia gene in areas with high incidence of malaria.
Chemicals
Chemicals
A drug called "thalidomide" was marketed as a mild sleeping pill in 1957. Even though it was deemed safe for pregnant women, it caused thousands of babies worldwide to be born with malformed limbs. The damage was revealed in 1962. The thalidomide disaster is one of the saddest episodes in pharmaceutical research history.
Radiation
Radiation
Radiation from the sun as well as radiation from the ground can change DNA. Nuclear accidents release large amounts of radiation that can affect plants as well as animals. See the picture to the left.
Biologist Timothy Mousseau has spent years collecting mutant bugs, birds and mice around Chernobyl and Fukushima. In a DW interview, he shares some surprising insights into the effects of nuclear accidents on wildlife.
These firebugs are mutants. Some of them are missing their distinctive "eye spots."
Non-Homologous Crossover
Non-Homologous Crossover
During a normal process called "cross over" homologous chromosomes can exchange information. Scientists think that crossover is a method to repair mistakes in the DNA.
Sometimes, the exchange in information happens between different chromosomes. This mistake results in gene duplications and other mutations within the genome.
Frog Mystery
Frog Mystery
In 1995, students at a middle school in southern Minnesota discovered one-half of all the frogs they caught in a nearby pond were malformed. This was national news. In fact, 6.5 percent of 13,763 frogs collected were malformed. Frogs had missing limbs, missing digits, extra limbs, partial limbs, malformed jaws, and missing or extra eyes. Scientists believe that chemicals
Scientists are still trying to discover what was the cause of these types of mutation. Some think the mutations may be caused by a combination of chemical pollution, predators, parasites, and nutritional deficiencies.
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