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EFFECTS OF MUTATIONS The changes in nucleic acid sequences by mutations include substitution of Nucleotide Base-pair s 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 Intron s, or because they do not change the amino-acid sequence, due to Redundancy of Codon s. 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-ray s 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 did not only mutate genes in fruit flies, but also had effects on the genetic makeup of humans.Campbell, Neil A. and Jane B. Reece. Biology. 7th ed. San Francisco, CA: Pearson Education, Inc, 2005. NATURE OF MUTAGENS Mutagens are usually Chemical Compound s or Ionizing Radiation . Mutagens can be divided into different categories according to their effect on DNA replication:
The Ames Test is one method to determine how mutagenic an agent is. EXAMPLES
MUTAGENS IN FICTION Usually in fiction, mutagens are capable of completely changing the form of the recipient.
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