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LEQ: What can go wrong in this process. 10.16. Mutations. A change in the nucleotide sequence of DNA Ultimate source of genetic diversity Gene vs. Chromosome. Gene Mutations.
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Mutations A change in the nucleotide sequence of DNA Ultimate source of genetic diversity Gene vs. Chromosome
Gene Mutations • Base Substitution – replacement of one nucleotide with another, change to final protein is minimal – 1 amino acid or no change at all • Silent mutation – base change codes for the same amino acid • Missense mutation – base change codes for a different amino acid • Nonsense mutation – base change codes for a stop codon
Gene Mutation • Frameshift Mutation – insertion or deletion of a nucleotide; changes the reading frame of the mRNA codons; can result in different amino acids from the point of the mutation on; major change to the amino acid sequence of the protein
Chromosome Mutations • Mutations that effect multiple genes • Deletion – loss of part of chromosome • Duplication – doubling of part of a chromosome • Inversion – changing the gene order of a chromosome • Translocation – crossing over between nonhomologous chromosomes • Nondisjunction – failure of homologous chromosomes or sister chromatids to separate during meiosis or mitosis
Mutagenesis The creation of a mutation Spontaneous mutations – mistakes in replication Mutagen – chemical, physical, or biological agent causes the mistake
